In the escalating product race between Denon and Marantz, both companies have introduced a range of high-grade disc players and amplifiers that have helped to push the boundaries of what's commonly referred to as 'state-of-the-art' in the world of hi-fi.

The Marantz SA-7S1 is an excellent example of this. It's a stereo-only model and is Marantz' best CD/SACD player to date, from a range so far known as the Legendary Series.

It's not a rehash of anything that came before either, and that includes its spiritual predecessor, the mighty SA1, which sold for around the same price, until it was discontinued in 2002, leaving a top-end gap.

The external casework and general presentation owes much to the more recent CD-7, but with subtle changes. It has many of the same trademark features, including a copper-plated chassis and an unusually solid, low-resonance dual-layer base.

The mechanism is a new in-house design based on a disc tray fabricated from 10mm thick solid aluminium to reduce resonant behaviour and to inhibit internal noise radiation. Where other players use opto-couplers to provide ground plane separation between different functional areas of the circuit, the SA-7S1 uses digital isolators using Giant Magneto Resistive materials from Swiss company IsoLoop.

A key piece of the internal digital clockwork is the PEC777f2, which performs multiple roles, acting as a digital filter, DC filter, noise shaper and eight times oversampler.

Features include selectable absolute phase inversion performed in the digital domain, which should (and to our ears, does) mean no unwanted side effects, and an input for an external high-precision clock.

The latter parallels a similar facility found on some other players, from Teac Esoteric and dCS, for example, and makes the SA-7S1 capable of locking onto clock signals of 44.1, 88.2 and 176.4kHz presented to a rear panel BNC.

There is no Marantz-branded clock available, however, even in Japan, and we didn't have any third-party clock to try. Our prior experience with such devices is that some players - for example Esoteric - tend to benefit, but in other cases the result is merely a difference, which is difficult to describe as better or worse.

The obvious quid pro quo is the additional cost of the clock, which is likely to be of the same order as the player itself.

The power supply is described as having a choke input. This is nothing to do with choke regulation, Musical Fidelity style, which some suggest make amplifiers sound as though their bass and treble run independently, like having two amplifiers in one box - an odd, and slightly disconcerting sensation.

We discovered during conversation with Ken that he has had a similar experience. The configuration used here is optimised for consistency across the frequency spectrum, and for overall dynamic range, which in his words is "difficult to do".

The display is said to be a low noise design, though it looks like a conventional enough fluorescent design. Standard optical and coaxial digital outputs are available from CD only, but they can be switched off when not required.

And like virtually all self-respecting high-end players these days, the analogue audio output is available in balanced and single-ended form. The SACD section delivers text readouts from text-enabled SA discs, but this sadly doesn't extend to CD Text, which would have been good. So would a smoother scrolling text display, but that's just being pedantic.

The SA-7S1 also has user-selectable output filters - similar to those available on the SA11-S1 - which involves three filters for CD, which also have an influence on the SACD output, see later. The SACD settings include the nuclear option of no active filtering at all.

There is also a DC filter (a high-pass network whose roll-off is set at 1.7Hz) plus a noise-shaping option that can be selected. The digital outputs can also be deselected, which is worth doing.

It goes without saying that everything Marantz knows has gone into reducing jitter. The player includes a fully shielded Super Ring (sic) transformer, and fully balanced internal signal architecture.

As usual, Marantz specifies a discrete HDAM output buffer, known as the HDAM-SA2, which offers a short, direct signal path and fully balanced topology; a more refined circuit than in previous versions.

The player looks wonderful, and handles discs well, with faster disc identification speeds than many SACD players, and rapid track access times, too. The remote control will also handle the basic functions of Marantz amplifiers, and is generally well-designed, though we've seen better.

Building an appropriate system around the player was clearly going to be a key to assessing its performance, but luckily with The Collection getting under way at around the same time, this was not too much of a problem.

The matching Marantz amp wasn't available, but I did have access to a Pass Labs pre/power combination, the X1/X150.5, which were used in balanced mode using Nordost Valhalla balanced interconnects (the new high-end Odin cables were not ready in time for this test).

I did, however, have an EMM Labs CDSA player, which was introduced towards the end of the test as a kind of yardstick. The main speaker was the Mordaunt-Short Performance 6, which is relatively inexpensive for a high-end model, but functions as a high-end design in every way that counts.

Better still, the combination of player, amplifier, speakers and cable fortuitously turned out to be particularly well balanced; the slight leanness of the Mordaunt-Short and Nordost was offset by the warmth of the player and amplifier.

Given the reputation that the Performance 6 has, the bass from the combination was superbly realised and remarkably well developed, to the extent that the use of the matching subwoofer was simply not deemed worthwhile pursuing, even though one was available.

Partly, however, this was down to timing - or rather the lack thereof. All the equipment was very thoroughly run in, with hundreds of hours on the clock in the case of the EMM Labs and Pass Labs equipment, while the Nordost cables and Mordaunt-Short speakers have been in almost daily use for a very long time.

We've taken some pains over specifying the test context to underline our confidence in the findings. In the final analysis, there was no difficulty in nailing down the character of the SA-7S1.

Fundamentally, this is a unusually musical player, one that works brilliantly with CD, and even better with SACD given discs of a suitable calibre - which are not always easy to find. As on previous such tests, some of the very finest sounds came from discs on the M&A label, including (but not limited to) their remarkable sampler.

In any case it was easy to hear what the Marantz was doing from almost the first bar of the first disc tried (Gitana, from llama by Silvia Perez Cruz & Ravid Goldschmidt), which has a soft, yet incredibly tactile sound - a very difficult trick to pull off, and one that requires remarkable sensitivity.

In a way this sums up the SA-7S1. We have considerable experience with such players, and this has involved listening to quite a few high-end CD and SACD players over the years. We cannot recall another player that makes music-making sound so easy, so unstressed, so facile.

It's not that there's any lack of detail here, nor of dynamics. On the contrary, it all happens a bit like a conjuring trick.

There's no hint of strain, and difficult combinations of sounds, subtle layering of instruments and voices, for example, just seem to float out of the speakers. No other player in our experience can beat the Marantz in the way it manages the difficult technical trick of sounding like music.

It's easy going yet well disciplined, and in the end we had an impression of a box that does its job without sounding in the least bit mechanical, or processed. For most discs, the default (first) filters delivers the best, most natural sound by a narrow margin, but it's essentially a matter of taste and worth experimenting with.

It is almost as good with CD as it with SACD. The difference is often just the inherent difference in the quality of the recording rather than the format, but there are exceptions, such as the M&A recordings already highlighted, and some others from Pentatone for example.

It's a remarkable tour de force and we're being cautious when we pronounce this as arguably the finest player available. It's also far from expensive for a machine with such ambitions.

If you want a disc player that will do the very finest musical job possible with your CDs and SACDs - the only really serious remaining audio disc formats - the Marantz SA-7S1 can even be considered a bargain at £5,000!