Depending on your viewpoint, the £3,740 ElectroKID system is either a serious and successful attempt at wringing the best possible sound out of an Apple iPod, or a rich audiophile's folly.

Actually, it's both, and we should love it for being both.

The ElectroKID is formed of two products from two different American high-end manufacturers - Krell and MartinLogan.

Bringing out the best in the iPod

The connection is Absolute Sounds, the UK distributor for both products. Ricardo Franissovici, Grande Fromage of Absolute Sounds, realised that the combination of iPod 'interface' and active loudspeakers could deliver the sort of sound quality that even Apple might not have expected from the ubiquitous iPod. And so, the ElectroKID was born.

The name itself is a portmanteau of 'electrostatic loudspeaker' (the MartinLogan Purity) and 'KID', which is itself an acronym for 'Krell Interface Dock'. Technically, it should be 'KIDelectro', but that sounds way too 1980's!

Incidentally, if you type 'electrokid' into Google on the interweb, you get a lot of DJs before you get to this system.

The Krell Interface Dock was the big audiophile controversy of 2007, because it was the first iPod-related product from a big name high-end brand. And, like all controversy, it has set the trend; at the CES 2008 we saw products like the Wadia 170 iPod transport follow in the footsteps of the KID.

A dock for all iPods

The £1,350 Krell Interface Dock is essentially an iPod dock combined with line preamplifier. It has both balanced and single-ended inputs, a composite and S-Video connection for video, and an RS232 port for those using high-end Crestron/AMX-style remote control systems.

It also has an auxiliary line-level input mini-jack on the front panel, for those wanting to use a digital audio player that is not of the iPod family.

Krell has been canny with the universal docking connector. Inset into a silo on the top of the KID, this has four little clear Perspex rods that wheel back and forth to make a snug fit for the iPod. So, you can guarantee an iPod Nano will sit just as robustly as an iPod Classic.

The KID does not crack the digital code within the iPod, but instead has mild filtering in post processing to help give the signal the best possible start in life (there's also subtle treble and bass tone controls, which are useful when trying to improve a lot of compressed audio sources).

Missed a trick

Strangely, given the fact that every single company in the audio industry has latched onto the iPod as potential saviour of their business, precious few exploited the fact that the iPod actually delivers a differential output. This means it's a doddle to run balanced outputs from the Apple player, but the KID is the first product to take advantage of this.

Applause for Krell and dumb points all round to everyone else for missing an obvious trick. Krell runs its differential amplifier circuitry in Class A, so the KID runs warm - not hot enough to reach for the Calpol, though.

Incidentally, Krell is considering a second iPod product - a full preamp with docking capability, called Papa Doc, although presumably not named after the possibly insane mid-20th Century Haitian dictator, Francois 'Papa Doc' Duvalier.

Powerful bass

The KID is joined by the MartinLogan Purity loudspeaker, to form the ElectroKID system. Last year, MartinLogan launched two entry-level speakers - the passive Source and active Purity. You could be forgiven for expecting the only difference between the two speakers to be the amplifiers, given that they were launched so close to one another.

In fact, the two have significant differences, especially in the bass. Yes, both share the same CLS Generation 2 electrostatic treble/midrange panel, housed in ML's rigid 'AirFrame' curved aluminium housing, and both have a broadly similar footprint, but where the Source features a single 200mm bass driver, the Purity sports a pair of 165mm units, driven by a built-in 200-watt amplifier.

There's a three-position bass control at the rear of both speakers, for +3dB, flat and -3dB, and its best to experiment. There's even a set of speaker terminals for those who want to drive the stators from an amplifier and that turns the internal amp into a subwoofer driver, although that's effectively irrelevant in this case.

Space to breathe

As ever with MartinLogan speakers, the Purity needs a lot of air - a good metre from the rear wall and half a metre from the sides.

As a high-end partnership, the two fit snugly together, although there's one small sacrifice in reality - the MartinLogan speakers don't accept a balanced input, so although the Krell KID takes advantage of the differential output of the iPod, that advantage is not passed on here.

Still, unless you have to use more than 5m runs of interconnect cable 'twixt KID and Purity, it's doubtful you would gain much by going balanced anyway.

The limitations of compression

Part of the issue with any dock is the quality of the recordings made to your iPod.

These can be so variable that they can make or break a sound, and many's the time low-fi systems actually do better than their high-end brethren in this context because small, cheap speakers are less demanding and thus, do not highlight the parts where data has been sacrificed at the altar of disk space.

In contrast, a full-range audiophile-grade system can throw the limitations of data compression into sharp focus.

Choose your formats wisely

So, if you are planning to use a take-no-prisoners replay system, you need to be just as resolute in your choice of format; AIFF or WAV give you bit-for-bit transfers, but with the concomitant disk-eating properties of storing 650MB or more per CD, Apple Lossless (as the name suggests) works like a zip compressor and does not interpolate the music itself.

You are still looking, however, at nigh on 300MB per CD.

Then, there's AAC and MP3; consider 160kbps AAC and 192kbps MP3 files as a bare minimum for use with the ElectroKID and if you can go higher (both go up to 320 kilobits per second), do so. You still get hundreds of hours on a single iPod (400 hours of music on a 60GB model sounds about right), but at least they are all listenable.

There's even the choice of iPod to consider. Naturally, your iPod has to be second generation or later to sport a docking port. But there are also some who reject the iPhone and iPod Touch on audio grounds.

Exciting sound

There's a symbiosis between the two non-Apple products that bespeaks quality. In other words, the KID and the Purity sing together beautifully. The Krell KID is more of a preamp than a dock and the improvement that it brings to the Apple sound is quite remarkable.

You get a vivid, exciting and clean sound with a surprisingly fine soundstage... something far better than the flat, pinched 2-D sonic disappointment that comes when you usually hook your iPod to the hi-fi. All this without even tangling with digital code must mean Krell is doing something right.

The sound is perhaps drier than typical Krell products, but is still an excellent presentation.

The MartinLogan side of things is not too dissimilar from the performance heard in the Source loudspeaker we recently tested.

The extended, smooth treble, the open mindrange, that effortless sense of disappearing loudspeakers and the well-integrated dynamic bass are all re-issued here.

From one extreme to another

The big difference between this speaker and the passive version is even better bass control, depth and integration; having that 200 watts on tap really brings the speaker to life and helps bring out the best in the KID. It gives the iPod sound a cohesiveness that it seems to so sorely lack in other settings.

Even the bass and treble controls - usually so alien to any Krell-loving audiophile - have a place here. Unlike most modern CD recordings, it seems that those squeezed into the iPod comfort zone are compressed at the bottom end and over-emphasised at the top.

Worse, this seems to have become the norm for modern pop and rock releases, perhaps to make them sit more comfortably in tinny little iPod headphones. The mild degree of tone shaping that goes on thanks to the KID helps shape this.

Justifiably pricey

That the iPod can be controlled by the credit card remote is good, but the logic driving the remote is pure Krell - it's not confusing, but neither is it the genius iPod interface.

We've heard many aspiring high-end iPod-based systems, but this is the best of them (it's also currently the most expensive of them too, these things may be related).

In some respects the Purity speakers are perfectly made for the iPod, if using good-quality sound files - the openness of the midrange and smooth, clean and extended treble fit the Apple sound perfectly, where cone-and-dome systems (especially metal dome tweeters) can sound brash and hard.

Also, because electrostatics take the emphasis off dynamic range, this helps take the edge off very mild compression, which always sounds too compressed on dynamic box speaker systems. The Purity designs do have a dynamic bottom end and that also fits the iPod profile.

Disappointing video quality

If there's a limit, it's in the video output.

In fairness, this is as much the fault of the Apple device as it is from the Krell KID, but composite and S-Video connections are relatively weak in today's HDTV world.

Others have shown (although not, as yet, launched) upscaling docks that bring the iPod video quality a nudge toward DVD-grade video goodness, but here the picture quality is indistinct and blocky, on both outputs.

We want to ask whether this system makes you reach for the off switch on your CD player, but this is wholly the wrong question. We doubt this will be the only system for
those who invest in it, and many will be considering the ElectroKID as a useful adjunct or complement to their existing high-end hi-fi.

In that context, the ElectroKID is a remarkable pairing.