Classé's new CP-800 preamp is less expensive, yet significantly more well featured than its predecessor the CP-700. In fact, it has more features than any dedicated two-channel preamp we have ever encountered!

For starters, it has digital, as well as analogue inputs and, of these, two are USB connections; one in the front panel for your Apple device and another on the back for a computer. Then it has five output channels with which to incorporate a second system or extra power amps and subwoofer(s) and that's only the connections.

Inside the sleek aluminium casework it's stacked with technological firepower, including bass management, so that you can optimise low-frequency performance almost regardless of where speakers are placed and parametric EQ.

If that weren't enough it also has something we've not seen on a high end preamp since the seventies; tone controls. All this with barely a button in sight thanks to a 16:9 touch screen.

Better than any CD?

The most controversial thing about the CP-800 however, is that Classé head of sales, Dave Nauber, claims that his iPhone sounds better through it than any CD transport. The front USB extracts a digital stream from your iDevice but that is fighting talk in our books.

When HFC met Alan Clark, the Scotsman who designed it (and the rest of the Classé range), he wasn't quite so bullish but did claim that the USB input could outperform the S/PDIF – which is pretty controversial itself. Alan has come up with a variation on the USB receiver, which he claims is superior to all the alternatives on the market.

He accepts that the asynchronous route chosen by increasing numbers of serious USB DAC-makers is better than the synchronous approach found in more affordable convertors, but has added a twist which is said to make the CP-800 a world-beater with this computer audio link.

Clark calls regular asynchronous USB interfaces 'non-optimal' because the ground noise that is inevitable with computer sources pollutes the clock and the DAC in the receiver. His solution to this has been to add an FPGA (field programmable gate array) between the USB microcontroller/receiver and the DAC, as a means of isolating both it and the audio clocks within the preamp.

The USB receiver has its own clock but it's impossible to fully isolate this because the noise levels are very high within the chip, The FPGA recovers only the data from the incoming signal and uses the precision clock within the CP-800 in order to minimise jitter.

The preamp also has an unusual power supply (PSU). One reason why it costs less than its predecessor is that the PSU is onboard rather than being in a separate box, but that's not the only difference. The CP-800 has a switched-mode PSU that operates at very high frequencies, which its claimed makes it less noisy than traditional linear supplies. It also makes it more efficient (as is usually the case) and this product hits the EU target of sub single-watt power consumption in standby.

Classé also uses power factor correction, which maintains a constant load on the mains. As a result it should benefit other components in the system, because they are not having to deal with a fluctuating mains supply. We would expect a power amp to modulate the mains, but were surprised that this is also considered an issue with preamps where power requirements cannot be that great.

Unusually for such a complex product, PCB layout is done by a lady called Cheng, who Clark describes as the world's most patient electronics designer, because she does it all by hand. This is because auto-routing cannot achieve the results that are possible when the effects of each component in a multi-layer board are taken into account.

As a result the motherboard on the CP-800 does not look as neat as you might expect, rather it has an organic appearance because signal paths need to be kept away from the noisier elements in the circuit.

Flexible friend

The CP-800 is superbly built; Classé knows how to put a product together and how to finish it better than most. Many build heavier, shinier and more bolt-laden products, but few highend companies are able to execute their products to this standard.

It is also replete with inputs, 15 in total including balanced and unbalanced analogue in and outputs, all the usual variations of digital input and the 12-volt trigger outputs beloved of North American manufacturers. There's even an RJ45 Ethernet socket which will allow the preamp to stream content directly when a future software update is made available.

Those extra three outputs are unusual on a two-channel preamp, but allow the use of two power amps per channel, plus a single subwoofer, or even up to three subwoofers. There is the option to configure all the in- and outputs, so that one input could be unity gain and use a connected sub, while the others just use the main two channels.

Inputs are nameable and can be assigned a specific amount of gain and/or balance setting. We seriously doubt whether there is another two-channel preamp that is this configurable and flexible, it is clearly a variation on a multichannel processor in this respect.

The iPod user will be pleased to read that it's happy to work with most versions of the popular device including Nano, Classic and Touch, not to mention iPhones and iPads.

Laptop, not phone

A carefully ripped CD sounds better played back from a computer than the original disc played via S/PDIF from a decent CD player. The difference isn't even subtle to be honest, the file produces music that is more revealing and considerably more interesting. A live performance of solo piano is extremely convincing, transporting us to the original venue, thanks to the stature of the instrument and the scale and nature of the acoustic being so palpably real.

Perhaps the S/PDIF input has one hand tied behind its back for the purpose of making the USB input sound better, but that seems unlikely. Especially when you compare it with the USB input of our reference DAC/ preamp (the Resolution Audio Cantata) which sounds almost flat by comparison. Clark has clearly done a fine job with this input and raised the bar for the genre as a whole.

As a preamp with analogue signals, the CP-800 has a hidden secret that must be unlocked for its full potential to become apparent; this is the 'analogue bypass' tick box. Sounds simple, but you need to track it down and tick it for each analogue input, otherwise the DSP gets in the way and undermines performance.

Once this had been sorted analogue signals are reproduced in a coherent and well-integrated form, with excellent image depth and width. It also has fine bass extension and articulation, not as fast as the best perhaps, but easily as deep and solid. It has a smooth, clean presentation, rather than one that emphasises the midband, in order to give the impression of greater transparency, such as you can find with valve preamps, but neither is it dry nor fine grained in the style of many solidstate devices.

The Classé doesn't have a phono stage, but can reveal the finesse of a good external one such as the Trilogy 907. Stevie Wonder's Superstition can be a little uncomfortable because there's so much low-frequency energy, but the CP-800 keeps everything under control and lets the all-important power of funk ooze into the room.

It's also a highly detailed presentation with layering that is often masked in lesser components. We were using the remarkable D'Agostino Momentum power amps, but the sound was nonetheless rich and deep in tone and scale.

Playing an iPod Touch via the front USB input elicited a pared-down result by the standards of more traditional sources, but a vibrant, clean and crisp one that's devoid of grain which can't be bad. It's in the same league as the better digital docks if not the best in class. We didn't have an iPhone, but if one could outperform a CD transport then this reviewer would eat his hat.

We didn't have any subwoofers around with which to assess the various ways in which their potential can be harnessed but had a go with the tone control, which is factory set to operate as a tilt device ala Quad and works in a subtle but distinct fashion. This, by the way, is another first in signal processing.

We also looked at the EQ options and soon realised that you need some decent measurement equipment to make sure you are going in the right direction. There are five filter options per channel and each of these are adjustable for centre point, level and Q. Useful if you want to iron out a bass hump, but best left alone if you're happy with the balance au naturel.

Ready and willing

This is an immensely well-featured preamp with the power of a multichannel processor under the lid. As a fair amount of the budget must go into this side of the build cost, it's not the most nimble example on the market when it comes to pace, but it does a stunning job with signals that emanate from a computer, better than we've previously encountered, in truth.

If you are looking for a totally future-proof preamp that can be used to not only make subtle alterations to tonal balance for those great, but poorly recorded albums, but can also assist with room balance on a per channel basis, then the Classe CP-800 is in a field of its own.

The original Elicit, we were astonished to be reminded, appeared in 1990. Any resemblance to the current amp is superficial at most, as this design is new in concept, specification and design.

It's an 80-watt-rated amp built into a familiar-looking Rega case. In common with most current Rega electronics, it incorporates a heatsink on the underside: but since that's not adequate in that position for two 80-watt channels there are also internal heatsinks at each side of the chassis.

All around the centrally mounted mains transformer are the components, mostly surface-mounted, that do the controlling and amplifying. It's not a lineup of everyone's favourite parts, and there's plenty of evidence that the design is unique in several ways, though some features are familiar enough.

Inputs are switched by relays and volume is adjusted via a Wolfson electronic control, while output is handled by modern bipolar transistors with onboard temperature sensing.

The six regular inputs are line-level by default, but an internal phono stage is an option. There's also a power amp input for future expansion or upgrading.

One area where Rega is very much in line with a lot of audiophile thinking is power supplies and there is extensive regulation of supplies for different stages of the amp. On the other hand, the mains transformer, while perfectly capable of supporting the output power rating, is not as over-sized as some.

To a large extent, good regulation will compensate for this and if cost is in any sense an issue it's not always the most efficient route to put in a huge transformer.

Sound quality

One of our listeners just didn't quite click with this amp, though he acknowledged that it has many strengths, especially soundstage and scale. Despite that, he missed some clarity and insight in the sound.

That's a shame, because according to his colleagues he was missing some full-bodied, red-blooded music-making of considerable emotional power. The fact is that the individual concerned is one of our fussiest regulars about dynamics and pace, from which it appears that this isn't the most dynamic amp ever. But it's far from the least and in many ways it has a very good line in dynamics, it just lacks the last word in 'kick'.

It also has very fine bass. As one would certainly hope at this kind of price, it's extended, but it is also exceptionally clear and well tuned, making low melodic instruments unusually easy to follow. This same quality provides a great underpinning for multi-layered music and sounds like symphony orchestra benefit with excellent clarity and tonal differentiation between the instrumental groups.

Meanwhile the excellent imaging helps maintain a sense of precision which proved especially useful in our track of unaccompanied voices. Just occasionally the sound can seem a little too bright, but on the whole treble is well balanced and midrange is nicely neutral.

And despite our observation above about dynamics, the rhythmic flow of a piece of music is well presented, with an unhurried but vigorous sense of purpose.

With its track record in audio now exceeding three-score years and ten, Quad remains true to its original aims in offering unique audio products that are immediately recognisable.

The Elite range, which over the last year or so has replaced the respected 99 Series, aims to incorporate audiophile design in small, smart and easily connected matching units, with source and amplification components sharing a basic case design.

They can all be connected with the usual phono sockets, but Quad's default hookup is the 'Ampbus', a 15-way D socket on the back of each unit which is connected to the next unit in the chain with a supplied ribbon connector, carrying balanced audio (and control) signals.

There is a stereo power amp in the range, but for this test we chose a pair of mono amps, each rated at 150 watts output. There are few things simpler than a mono power amp, but these have one unusual feature in the rear-mounted switch which selects their channel from the six potentially available on Ampbus – you need to set one to '1' and one to '2' for stereo or you'll get mono sound. (Or use the phono input.)

The preamp features three phono socket line inputs, as well as Ampbus, plus an RIAA phono input. Internally it's very well filled with high performance op-amps and electronic switching and attenuating components, the complexity partly due to the inclusion of tone controls (defeatable, of course) as well as the comprehensive in and out options.

Both pre and power amps are neatly built with entirely through-hole components of good quality.

Sound quality

This is another amplifying ensemble where subjective performance seems to be dominated by perceived minor irregularities in the treble.

In unusually analytical vein, one listener suggested that there is, paradoxically, less edge and bite to the sound, but slightly more sibilance. Impossible? Perhaps not, if one accepts that the treble is actually quite a broad band and 'edge' and 'sibilance' belong to different parts of it.

Our experience is that sibilance is a function of the octave below the very top one, while the highest octave of hearing can often manifest as subjective 'edge' – and also, on some occasions, very much further down the spectrum, having a knock-on effect on bass.

If there is any effect on the bass here, then it's clearly very minor. There's an unfussy approach to bass that works well. When we made a point of listening for low-frequency sounds, we found they were invariably strong, clearly focused and well-pitched, too when appropriate, but they never leap out.

Midrange is also very well balanced, while imaging is wide, deep and well defined. And then there's the question of dynamics, which is complicated by the treble character noted above. Longer-term dynamics work very well and low percussion fares best in this regard, but sudden loud sounds from bright melodic instruments do seem a little polite by comparison with more overtly dynamic amps.

The sound has good detail, though and overall this is a pleasing and rewarding combination for long-term listening.

The Moon i3.3 is one of a growing number of integrated amps to include a digital input, either as standard or, as in this case, as an optional extra.

It makes a lot of sense: you don't need a huge amount of circuitry to make a pretty decent DAC and if you've got a case and power supply already it's quite a simple addition.

Electrical, optical and USB connections are provided, with the actual conversion being done by a good-quality, recent DAC chip supported by good passive components and onboard supply regulation. Sample rates up to 192kHz are supported (48kHz on USB).

The features are simple, with just four analogue inputs at the rear and one (mini-jack) at the front, next to the headphone socket. Output is rated at 100 watts per channel, the output current conveyed via two pairs of transistors marked with Moon's own part code.

The inside of the amp is quite busy, with circuits surrounding the mains transformer. Components are a mix of through-hole and surfacemount and also a mix of discrete transistors and integrated circuits. Input switching is electronic, but the volume control is a motorised potentiometer. Basically this is a fully traditional integrated amp plus digital input, but it is a very solidly built one and little touches like very high-quality output terminals add to the appeal.

Sound quality

Looking at our listeners' notes and also taking into account our sighted listening, we're drawn to the conclusion that this amp attempts to do everything. As a result, the i3.3 is a good all-rounder: its only problem is that it doesn't excel in any one area so risks being damned with faint praise.

It manages longer-term dynamics rather well, with nice swells over a period of a few seconds of more, but it can be a little underwhelming with sudden drum hits, unexpected piano chords and the like.

Conversely, it does very well with voices, which are natural and very communicative. Tonal balance is mostly good, though there can sometimes seem to be a little restriction of both frequency extremes.

In the treble it's really only the very highest frequencies that are affected, so most of the time one is not aware of anything amiss: it's only with exceptionally treble-rich instruments that one notices (a trumpet solo alerted one of our listeners, for instance).

Bass is a touch soft in the lowest octave or so, with a slight lack of extension and also of focus. Pace and rhythm work well, despite the dynamics limitations, with music moving along quite energetically and even urgently.

Stereo imaging is a little disconcerting, as it seems good in terms of extension in both dimensions, but lacks some precision in the placing of individual instruments. With large groups of players, though, the sense of specific bodies of instruments is impressive and adds beneficially to the overall effect.

One aspect that does slightly concern us about this amp is its lack of consistency. Usually there's some continuity of character between different pieces of music, but in this case our listeners ended up making some contrasting comments in different excerpts.

Nevertheless the general trend sense is of musical involvement.

There's no denying that the Densen B200 and B310 pre and power amplifier combination look uncommonly smart and timeless with their perfectly rectangular looks.

And also worthy of honourable mention is the impressive remote control, all metal and streets ahead of most of its breed.

The basic specification isn't too unusual, the power amp putting out a notional 80 watts into the usual eight-ohm load, while the preamp has effectively six line inputs.

There's an unusually prolific array of phono sockets, though, not least because there are no less than four preamp outputs. There are also two record outputs and a processor in/out loop. Vinyl lovers can add an internal phono stage, converting one line input to phono.

Pre-amplifying circuitry uses surface-mounted discrete transistors, arranged as neatly as soldiers on parade, with good-quality passive components and twin power transformers.

In the B-310 power amp, a large toroidal mains transformer dominates the case, while most active components are again surface-mounted. Large output transistors are thermally coupled to the base, relying on the case itself as a heatsink.

Gain is switchable between high and low settings, allowing for passive preamps. The unit is easily upgradeable to drive loudspeakers via Densen's 'SAXO' active crossover – the firm has long expounded the virtues of active driving.

Sound quality

Despite increasing similarities in technical performance between brands and models, it's still often possible to put a finger on a distinct sonic character in a piece of audio electronics.

In this case, there's something about the treble that makes the sound large, crisp and just a little bright. At best, it comes across as lively and attractive, making the most of musical dynamics and contrasts, with images that spread across the soundstage in a highly believable manner. It's easy to pick out details if one wants to, but the big picture is not sacrificed and there's plenty of opportunity to revel in the scale of a large orchestra or rock band.

Voices do well, most notably when there are several of them, with good individual sounds clearly distinguishable one from another. The downside of that treble character is that, for some listeners, it can cause something akin to a 'halo' around the sound; an aura of distortion or upper-harmonic ringing which significantly interferes with musical enjoyment.

Obviously it's not on anything like the scale of bad MP3 coding, for instance (which causes the same effect but in a thoroughly gross way), but it's the kind of thing that can be distracting even at very low levels. But most listeners seem to find the sound merely a shade bright.

It's not always the most energetic rhythmically, but bass is solid and its pitch is clearly defined. We also found the combination notably adept at driving different speakers without changing character.

Streaming digital music from your computer is a great idea, but it's also a challenging one for the non-technical.

Setting up such systems is getting a lot easier, but Apple's Airplay is about as easy as streaming can be. All you need is an Apple touchscreen device or computer and an Airplay receiver, then you can play whatever is on the source wirelessly through the receiver.

By combining the interface with the source cuts out a whole stage from regular wi-fi streaming systems. Micromega clearly likes the concept and is the first audiophile brand to make an Airplay-compatible integrated amplifier.

Library of titles

Micromega makes this distinction because Denon and Marantz both have Airplay-ready receivers and Bowers and Wilkins' latest Zeppelin Air is also in on the action. Make no mistake Airplay could be very big indeed.

Micromega's system is dubbed 'Airstream' for licensing reasons, but it's not exclusively designed for Apple sources; any computer using software called Airfoil (£15) from Rogue Amoeba can stream content to the AS-400.

The company incorporated Airstream into its WM-10, which has been around for over a year and is also based on an Airport Express module, but it doesn't have a Micromega DAC and power supply like this integrated unit, nor is it an amplifier.

What is crucial about this system is ease of set up. You don't need a computer at all, nor a wireless network: all the transmission and reception is done by the amplifier and your player. As well as streaming from your music collection you can also send content from Deezer, Spotify and Pandora albeit only via using Airfoil software.

The AS-400 is a 400-watt (into four ohms) integrated with three line inputs, an MM phono input and the ability to operate as a preamp or power amp alone. It's included because this is a Micromega IA-400 integrated amp with Airstream added, an extra that increases the price by over a thousand pounds!

Both amps have Hypex class D switching power amplifiers, one per channel, which are fed by a power supply with an extremely heavy toroidal transformer and four very large 10,000μF capacitors. It runs surprisingly warm for a switcher, but it's a pretty powerful one with not a great deal of ventilation or obvious heat-sinking.

Control is via a selection of front-panel buttons and volume knob or a densely populated system remote, useful if you have other Micromega components we guess.

Inputs can be named using a library of titles for the three line inputs but not for phono, Air or iPod. It's perhaps surprising that something oriented to Airplay should have the latter, but only the iPod Touch can transmit wirelessly.

We would also have liked to have seen a USB input for a digital output from an iPod or computer, but this is not included probably because it's all about streaming from such sources.

Set up is child's play, once you notice the little icon on the bottom of the iTunes window which allows you to select which network the computer/idevice streams to. When you plug the AS-400 in its Airstream logo flashes red, while it boots up.

You will then see MUSIC on your list of local networks and can join it with a default password. Then it's a matter of clicking on the box with a triangle at its base in iTunes and selecting the Micromega. Simple.

Zero-tolerance

In terms of build, the fact that the AS-400 is a variant on the IA-400 means you get the construction and finish that Micromega can achieve in a £2,797 product, which is good but not outstanding for the money. It only has single-ended in and outputs, whereas many competitors offer balanced at this level and the remote is a fairly standard OEM type.

Front and rear panels are machined out of aluminium and being able to change input name is useful, more useful, however, would have been a USB input or digital inputs of some sort.

Primare's (non-Airplay) i32 integrated (£2,200) has more inputs and includes two balanced pairs among them. It also has a rather more distinctive facia, with chunky stainless control knobs. It's less powerful at 120 class D watts per channel, but seems like better value on the face of it.

There are a few high-power integrateds in the same fiscal ballpark as the AS-400 and the better examples include ATC's 150-watt SIA2-150 (£2,599), Leema's 150-watt Tucana II (£3,425) and Bryston's 100-watt B100 SST (£4,899). These are all class A/B designs which are usually more expensive to build than class D types and all but the ATC have balanced connections, as well as more substantial casework than the £3,898 AS-400.

Build and spec is not everything, of course – power figures are notoriously misleading and none of these amps has the ability to stream either wirelessly or otherwise. But it's more than likely that there will be plenty more appearing in the coming year.

Power play

What first grabbed us about this amplifier is its power, the result lives up to the spec in many respects. It's got a powerful, but smooth-edged grip that controls the bass in a muscular fashion; it makes up for the lack of balanced socketry and heavy machining the moment you put something with a bit of welly in the player.

The immediacy and image precision with a pair of ADN speakers is nothing short of gripping; this is a speaker that likes power.

At this point we stuck a Primare i32 into the system to see if the price difference makes sonic sense. It does: the Micromega is considerably better at revealing space, the acoustic of the recording, not to mention its dynamics and timing. There really isn't any contest; you clearly get more for your money.

On the all-important Airstream front we used a Macbook to make a direct comparison between the laptop's optical output via a Stello DA100 Signature DAC and an Airstream feed. The latter produces a considerably wider soundstage in the context of a more relaxed presentation when using iTunes alone as the player, however if you add the Pure Music player into the mix this gives the optical output a significant edge by adding improved dynamics to the mix.

The Stello is a £750 convertor and Pure Music costs £80, so the combined cost approaches that of adding Airstream to the IA-400 when you take a decent optical lead into the equation.

As we also had Leema Acoustic's Tucana II to hand, this was brought into the fray to see how the AS-400 compared with something in the same price arena. It proved to be tonally richer and able to deliver greater depth and dynamics compared to the Leema, which produces a more solid, but less refined sound, which is a pretty good result.

Apple at its core

What is most appealing about this amp is being able to sit down with an iPad and play whatever you like, it's a world-class interface and the sound produced is clearly superior to that available with an analogue connection.

At heart this is a rather good amplifier: its musical, dynamic and has bags of power. Input selection is a bit limited and the build quality could be better, but if it's sound you are after then this hits the mark. And thanks to the Airplay factor, it's a doddle to set up and start enjoying.

Audiolab: the brand that launched a thousand hi-fi's. Many thousand, indeed. For many years towards the end of the 20th century, the Audiolab 8000A was the integrated amp to own as part of a decent-to-aspirational system and indeed plenty are still doing sterling service.

After the success of the 8200CD, we were even more keen to meet the successor to the 8000A; the 8200A.

This char-ming amp

In many ways it is strongly reminiscent of the hallowed original. The front panel is similar, the proportions are not far off and one strongly distinguishing feature remains in the central internal heatsink, cleverly arranged to vent through top and bottom of the case without allowing too much dust into the amp's innards.

Internal heatsinks like this are common now, but in the 1980s this was just about the first to dispense with finger-ripping external heatsinks.

Features differ significantly from the 8000A. There's no phono stage, for a start, which is a shame as that in the 8000A was always one of its big attractions. Audiolab doesn't currently have a single phono-capable product, but there are plenty of decent standalone phono stages around so it's hardly the end of the world.

The switch routine

On the other hand, there is an unusually sophisticated set of mode-switching options. The separate listen and record selectors are always welcome, but the 'Mode' switch provides options which other amps either don't offer, or at best offer with some rewiring and/or reaching round the back.

Some of these modes aren't entirely obvious but with thought it's clear they all have their use. 'Mute' is simple enough and 'Pre-Power AV' separates the pre and power sections, giving the option of connecting a processor between them. But why do we need separate modes for 'Pre', 'Integrated' and 'Pre-power'?

In the last, pre and power sections are connected internally anyway, while instead of having a 'Pre' mode one could simply ignore the power stage. The clever part is that in Integrated mode the preamp outputs are disabled, while Pre-power activates them. Pre disconnects signals to the power amp section. This means that one can have a remote power amp connected which is only active when one wants it to be, while the 8200A's power section can be disabled when one doesn't want to use local loudspeakers.

Yes, some of this could have been done with speaker output switches, but the main thing is that it gives exceptionally flexible control over the amp's constituent parts.

Three line inputs at the rear are joined by three input/output pairs, rather quaintly marked 'Tape 1', 'Tape 2' and 'Video'. Well, recording outputs and associated monitoring inputs, anyway and, of course, you can use any of them for perfectly ordinary line inputs.

The preamp output appears on two pairs of phono plugs and speaker terminals are likewise dualled, for bi-wiring and so on. A full-size headphone socket sits at the front.

The same, but different

In terms of amplifying circuits, the 8200A clearly bears some resemblance to the 8000A though there are changes – among specific points mentioned to us by the designers, the input transistors have been changed to a completely different type, while input switching is managed by relays.

Despite that, the main input selector is a motorised mechanical switch, which may seem bizarre but means that the positive and direct manual input of a front-panel switch is retained while adding the benefit of switching right beside the input sockets, plus remote control. The volume control is also motorised, naturally.

Rated output matches the original exactly at 60 watts. The circuit of the power amplifier section is unusual in the way it applies feedback. So the 8000A was well liked in its day.

But that was then... and it's very much our experience that the baseline of audio electronics performance has risen markedly over the last 20 years. We never expected to find the 8200A a poor amplifier, but we were a little nervous as to how it would fare against modern competition.

In the event, we had plenty of opportunity to try it out alongside amps of all sorts at similar prices and indeed a good deal more, covering various approaches to the sound/features/power balance.

As assured as ever

The short-form result is that the 8200A holds its own. It offers good, solid bass, well extended treble, lively dynamics, detail and all that sort of stuff and while it may not offer them in the sort of style you'd expect of £10,000-worth of pre/power separates, it follows the general 21st-century trend of coming uncomfortably close. Uncomfortably, that is, for anyone who's just parted with £10,000!

Where we really have to hand it to Audiolab's designers past and present, though, is to do with the way that this amp manages all that and still contrives to retain some genuine character of its own. Yes, 'character' can mean inaccuracy, but like many potentially risky things, in very small doses it's a very useful thing.

Basically, this is a very neutral amp. Listen to it for a while, though, and you start to realise that the sound has just a trace of charm that's all Audiolab's own. We first realised this with a familiar orchestral recording, in which we suddenly found our attention drawn in a slightly different direction from usual, more towards the middle-register instruments rather than the melodic violins and flutes or the low strings and heavy brass.

Having noticed that, we then found ourselves appreciating a similar phenomenon in other styles of music. Male vocals certainly benefit, but since in most music the middle registers are very much home to the 'backing', the commonest effect is to make that backing clearer and very slightly more present than before.

That wouldn't be so good if it meant the melody and rhythm sections were being sacrificed, but we never felt that to be the case. What does sometimes happen is that the melody becomes just a shade mellower, less bright and strident and, perhaps, that won't always be to everyone's liking.

Bass, by contrast, is consistently rich and full-featured through this amp, well extended and with good rhythmic drive and an almost palpable texture. But that lower midrange thing is intriguing and was what really had us coming back for more after a few evenings with the 8200A.

It brought home to us just how much information, in how many recordings, exists in that register and gave us renewed pleasure in several familiar discs. Superficially it seems like a tonal aberration, but (apart from the fact that there's no kink in the frequency response to support that) it's more to do with retrieval of detail.

Imaging, too, is particularly fine around that part of the frequency range and that's not to say it's noticeably lacking elsewhere as it's good to very good across the board. High-resolution digital sources seemed to benefit even more than CD, if our rather small sample of them is anything to go by, while LPs (via an external phono stage, of course) were less affected.

Rather usefully, MP3 downloads are typically a touch sweetened up by it, though we wouldn't go quite so far as to call them redeemed.

What's clear, though, is that this amp is just as capable of giving musical pleasure and excitement as its esteemed predecessor was back in the 1980s. Standards in general may have risen, but Audiolab got it basically right in the first place and the new revision merely tweaks performance in line with current products.

The increased use of music sources other than CD has led to the need for hi-fi components with a broader range of options. In particular, the ability to accept digital source material stored on computer hard drives has become an added factor.

With the Ethos, Pathos has created a powerful hybrid tube/transistor integrated amplifier capable of accepting a wide range of sources – from balanced analogue via XLR, to digital via USB (via an optional DAC).

Here's an amplifier that meets the needs of two-channel purists, while catering for those interested in using digital sources.

Five alive

The Ethos makes provision for five unbalanced line sources via RCA phono plugs, two balanced line sources via XLR plugs, plus four video inputs. There's an optional built-in 24-bit/192kHz digital-to-analogue convertor, with inputs via two USB ports type A and B, and a S/PDIF co-axial RCA socket. A stereo pre-out and mono subwoofer output, are also provided.

The preamp section is entirely tube; pure Class A and based around a pair or ECC88s (6922) valves, one each per channel. The power-amp section is a true dual-mono solid-state design that delivers around 100 watts per channel into eight ohms – or 200 watts into four ohms. It's also possible to bridge the output, creating a single-channel output of 270 watts.

All circuits are feedback-less. The electronic volume control has 180 steps with digital readout and is entirely resistive – using laser-trimmed resistors for accurate channel balance and precise adjustment. Each volume 'step' is around 0.5dB, allowing specific repeatable control of loudness.

An alpha-numeric fluorescent display indicates things like volume setting (in dB values), and input selected.

Specifications are impressive, with a claimed frequency response from 2Hz to 200kHz (+/- 0.5dB) and less than 0.01 per cent distortion. Each tube sits in its own little well and would be easily removable should the need for replacement arise. The tubes produced some heat but not that much – even though surrounded by casework, the tubes seem to run fairly cool, but during use, the casework gets mildly warm after an hour or so.

A slight mechanical transformer buzz was just audible with our review sample when sat close by, but this wasn't felt to be serious. The amp is fully protected against things like excessive temperature rise and accidental short-circuit. There's a relay-protection system that mutes the amp while everything warms up and settles down – this takes about 30 seconds.

After switch-on, the amplifier defaults to Input One (XLR) and the volume control is set at – 52dB. If you switch the amplifier off from the front panel, your previous volume and input settings are remembered. However, if you switch off from the wall socket, or disconnect the mains supply, your settings are lost.

Each input has its own individual volume control memory and can be set independently. This means you can adjust levels to cope with sources of differing sensitivities – a nice touch. There's provision to adjust left/right stereo balance, available from the remote handset via button five.

The remote allows volume control, input selection, mute, and lets you put the amp into Standby. It has six press buttons, but these are not labelled. This means you have to remember what each one does – a free memory test with each amplifier!

Massive beast

Weighing in at a hefty 20 kilograms, the Ethos is a massive beast. Just lifting it tells you it's a well-made piece of kit.

The casework features a combination of steel top and bottom plates, with heavy cast-alloy heatsinks and front panel. It's pretty large for an integrated and quite a bit deeper than usual. The heatsinks are extruded in the shape of the Pathos brand name logo when viewed from above.

The two valves each have their own little 'well' for protection, but the glass apex of the tube sits slightly proud of the top-plate – so take care not to place anything over them for fear of breaking the tubes. Although the amp doesn't get massively hot, you need to keep the ventilation slots clear.

The casework is very well finished and solidly built – oozing quality and class from every pore. The styling is a matter of taste; we love it. For sure, it's a big, uncompromising unit and not everyone will like the way it looks (the price is also fairly high for an integrated). However, given the features and facilities offered (balanced inputs, optional built-in DAC and USB inputs) you undoubtedly get a lot for your outlay.

This is a highly versatile unit that should be pretty future-proof. So it's a good investment for reasons other than sonic ones.

Immensely impressive

Straight from the box, the unit needs time to burn in. Initially, it sounds rather bright and forward. But after a week or so it settles down nicely, producing a winning combination of immediacy and clarity.

While it hasn't the smooth creamy richness you get with the best all-tube amps, the Ethos does have a certain tonal allure. It's very lucid and detailed, but not excessively 'toppy' or over-bright. The sound has excellent focus, lots of fine detail and there's plenty of power. The bottom end is taut and powerful, with better control than most transformer-coupled tube amps.

The Ethos features a MOSFET power amp and being direct-coupled (rather than transformer coupled like an all-tube amp), there's an immediacy that is immensely impressive. Transient attack is very good, and wide dynamic swings are handled with aplomb – the sound expands impressively, with no hint of compression.

The use of tubes in the preamp probably adds a degree of richness and warmth, but the Ethos is not obviously rose-tinted or soft. Listening blind, we're not sure you'd automatically register the use of tubes.

We initially used our review unit via its unbalanced inputs and sonically the results were extremely good. However, we later tried the balanced option and noticed a very worthwhile improvement in tonal depth and richness, plus a heightened sense of scale and dynamics. The sound seemed bigger and more dimensional. It was louder, too – by about 6dB.

However, even after adjusting volume levels to compensate, the unbalanced option never seems to match the extra 'something' we noticed with balanced. To exploit the balanced option, you'll need a CD player with balanced outputs, plus a set of balanced cables with XLR plugs at each end. These will obviously add to the cost, but we think you'll find the difference well worth it.

Mix of virtues

The Ethos is a sophisticated highly accomplished stereo integrated amplifier that is good enough sonically to appeal to discerning purist two-channel audiophiles, while offering lots of 'extras' to interest those looking for something more versatile. It's very well made and offers a lot for the money.

It delivers the kind of smooth refinement you expect from a good valve amplifier, but has the extra power, drive and control you get from solid-state. Given such a mix of virtues, it should enjoy a wide appeal.

Lehmann is a company that specialises in phono and headphone amplifiers. The Lehmann Audio Black Cube Linear USB is an unusual proposition in that it manages to be a headphone amplifier, a preamplifier and a DAC all at once.

Admittedly, viewed as a preamp, it's a bit basic, because it features only one analogue input, and the DAC has only one input which is USB (when this is active, that is when it detects it is connected to a valid source, the analogue input is bypassed). So really this is an analogue/digital input headphone amp with a volume controlled line output!

Heady power

Lehmann's idea of what constitutes a headphone amp is generous, with a full push-pull power amplifier output configuration. Of course, the power levels are lower than for an amp intended to drive speakers, but there are nevertheless four power transistors on heatsinks waiting to drive the load. And their ability to do that is impressive.

We obtained output powers of up to one-watt into low impedances and any kind of headphone, from 15ohms to 600ohms (which is pretty much the full range for dynamics), stand to receive at least 100mW.

We have to say that actually listening to any headphone when driven that hard is really not a good idea, but it's nice to know that at any sane level there's plenty of headroom.

Blue velvet

You may already have noticed from the photograph that there are two headphone sockets on the front of the unit, of which one disconnects the line output and the other doesn't.

Next to them is the volume control, a traditional mechanical type from the Alps 'Blue Velvet' range. It's typical of the whole unit in being a high-quality component and the unit is powered from a generous internal toroidal mains transformer.

The phono sockets and USB input are a bit jammed-up at the rear and only labelled underneath the unit, but it's all easy enough to deal with.

Flexibility is enhanced by a couple of little slide switches underneath the unit, which give gain adjustment in 10dB steps.

Pure and simple

Restricting ourselves to sensible listening levels, we tried this amp with various headphones from Grado, Shure and Beyerdynamic, and found it an excellent and fearless performer. It's slightly less at home with the lowest impedances (as typified by in-ear phones), with which it can develop a trace of tonal coloration, but across the range it is quite beautifully detailed and unconstricted.

It also does some very impressive things with bass; keeping it strong and precise but never accentuating it. Indeed, it's almost the perfect example of an iron fist in a velvet glove.

Treble is no less competent: sweet and open with minimal sibilance, though over-bright recordings are still going to sound that way, one of the undeniable drawbacks of headphones (plenty of recordings are just about acceptable on speakers, but simply sizzling on cans).

DAC to the test

All the above refers to the analogue input. We've mixed feelings about the digital input, though. It's good and indeed of its kind (using as it does a single, familiar, chip to receive and convert the digits) it's very good, but it's still not the equal of some of the very fine DACs that are around for £200-£300: we're thinking, of course, principally of the Cambridge DacMagic and the Arcam rDac.

Either of those could be had for about the price difference between the basic Black Cube Linear and the USB version and bothoffer higher quality and more fl exibility. In fact, either of those two could add a little resolution to this DAC and generally remove a veil or two between you and the music.

Of course, if simplicity is something you strive for and one USB input is all you need, it's much less of an issue and we can't deny that this is enjoyable via USB. Via line in, though, there's no question: it's a very fine headphone amp indeed.

Although solid-state amplifiers offer many practical benefits – smaller size for a given power output, cooler running, higher maximum power output and potentially lower noise – tube amplifiers promise a certain extra 'something' that many audiophiles seem to find irresistible. But is it all imagination and hype?

While tube amps might seem to hark back to the golden era of high-fidelity, do they really offer any tangible benefits over a good transistor design?

With its pure Class A output stage, the Unison Research S6 has all the right credentials. It undoubtedly talks the talk, but does it walk the walk?

Gutsy sound

Like most modern amplifiers, the Unison Research S6 keeps things simple.

It offers five unbalanced line inputs, a set of tape outputs and a single set of loudspeaker outputs. There's no built-in phono stage and no socket for headphones.

The volume and input selector knobs have a nice solid feel and the amplifier comes with a handsome wood-clad remote control that looks like a late '80s mobile phone.

Bear in mind it's actual output is 'only' around 30-35 watts and obviously, much depends on things like room size and the volume levels you like to listen at, but ideally it needs reasonably sensitive speakers to avoid running out of steam during loud climaxes.

Six EL 34 output tubes are used (three per channel) along with a pair of ECC 82s. Each output tube features user-adjustable bias and there's a moving-coil meter to help you set the correct value. If you remove the output tubes and mix them up, you'll need to check and reset bias again. It's very easy to do this and once set, you shouldn't have to adjust bias again – though it's worth checking every now and again, just to make sure things haven't drifted.

The S6 has a quoted output impedance of six ohms. Being a transformer-coupled amplifier, loudspeaker impedance-matching is more important with the S6 than it would be with an equivalent transistor amplifier.

With direct-coupled transistor designs, amplifier current-output doubles (in theory at least!) as loudspeaker impedance halves. To exploit this, some loudspeaker manufacturers produce speakers with a four-ohm impedance to squeeze more power (current) from the amplifier – basically it's a means of increasing speaker efficiency.

However, being transformer-coupled, tube amplifiers don't respond in a reciprocal manner and require matching; many offer a choice of four- and eight-ohm outputs, allowing you to match amplifier and loudspeakers with greater precision to maximise power transfer.

While manufacturers usually state the nominal impedance of their loudspeakers, the 'correct' impedance match is essentially the one that gives the loudest sound. By providing an output impedance of six ohms, Unison Research offers a compromise setting that should work well with most loudspeakers – though low-efficiency types with an impedance of four ohms will probably benefit from a proper four-ohm tap.

Being pure Class A, the amplifier runs pretty hot. Naturally, the six EL 34s put out quite a bit of heat, but, being as they're not enclosed by casework, they ventilate naturally. There's a stainless steel platform to radiate heat upwards, but the central section of the amplifier gets very warm during extended use, so don't leave a CD case there – it might have turned into a strange shape by the time you return!

Crucial influence

The S6 is solidly made, being built on a steel chassis and sporting a 2mm-thick alloy front panel with wooden inserts. Earlier incarnations of this amplifier had quite a bit of decorative wood to liven-up the visuals (and add a bit of damping?), but this new version is plainer-looking – albeit still very stylish in an understated sort of way.

While at £2,990 the S6 is not inexpensive, it offers good value given the quality of sound it produces. You could easily pay a lot more and not achieve anything like as good a sound – it's definitely an amplifier that punches above its weight.

Speaking of which, at 25kg (55Ilbs) the S6 is a heavy beast. This is a good thing, as it indicates massive transformers. Not just the main power transformer, but the two output transformers that couple the loudspeakers.

The latter have a crucial influence on sound quality. Way back in the late-1960s, eliminating the output transformer was one of the main reasons given for preferring transistor amplifiers over valve types – direct-coupling gave you a sharper, more immediate sound.

Much of the 'valve sound' (warmth, roundness, fullness, weight) is down to the fact that virtually all tube amps are transformer-coupled. Although having an output transformer adds an extra component, it also blocks RF interference and 'protects' the amplifier's output from the vicissitudes of the loudspeaker crossover. The downsides are things like added cost, possible peak level saturation and phase shift at frequency extremes.

Crisp dynamics

The S6 produces a very rich smooth alluring sort of sound that we found immediately likeable. It delivers a big weighty sort of presentation that's full-bodied and solid.

There's something 'right' about the combination of incisive clarity and rich pungent depth it offers. On naturally miked recordings of acoustic music (classical, jazz), it recreates vocal and instrumental timbres in a manner that's wholly believable and 'real'-sounding.

For decades now, audiophiles have debated whether or not valves sound as 'accurate' as transistors. But, how do you judge accuracy? Unless present when the recording was being made and able to hear exactly how it sounded live, it's difficult to say with authority what is or isn't accurate.

What you can say with greater certainty is whether or not something sounds believable and authentic. Judged in these terms, the S6 delivers results that are very convincing and real-sounding.

As mentioned earlier, at just 35 watts, it's not massively powerful. But, it definitely punches well above its weight and (in the nicest sense) cons you into believing it has all the power you could ever need – and maybe even a bit to spare. Leastways it does when partnered with reasonably sensitive loudspeakers – say, those over 93dB/W.

However, this is an illusion – if pushed too hard, the sound loses its dynamic clarity and transparency. While the S6's tonal balance has a honey-rich glow and warmth, the sound is not 'soft' or lacking in detail. Indeed, it's often remarkably tactile and incisive, with crisp dynamics and 3D stereo imaging.

At the same time, bass and treble extremes remain beautifully balanced and integrated, so that the higher frequencies never 'lead' the midrange and bass. The bottom end is clean and firm – maybe not quite as deep and powerful as certain direct-coupled transistor designs, but solid and weighty when it counts and free from smearing and boominess.

If you push the amp hard, the bottom end seems to compress slightly and the sound loses dynamic separation. But you don't hear the sound break-up as such.

For such a hot-running amplifier, the S6 sounds pretty good from a cold standing-start. It does become a little freer and more mellifluous after (say) an hour or so, but it's very listenable from the off (our review sample had seen some action at a couple of hi-fi shows and was more or less fully run-in).

During those all-important few minutes when we first got the amp up and running, we had an immediate 'I like it' moment – being smitten with its combination of smooth, lush warmth and crisp incisive clarity. It definitely delivers that airy, three-dimensional quality Class A amps are famous for.

Absolutely gorgeous

If you're new to valves and wonder what all the fuss is about, Unison's Research's S6 would be the perfect introduction. It sounds absolutely gorgeous, delivering that sweet glowing richness that tubes are famous for, without loss of bite or immediacy.

Indeed, it's the combination of silky smoothness and crisp immediacy that is so alluring. Power output is limited, but the S6 is one of those tube amps that's very good at covering its tracks.

Listening to it, you're rarely aware of its 'limitations'. It recreates the music with little sense of strain and sounds as though it has power to spare.