According to the company blurb, Flying Mole embodies the concept of "accomplishing the impossible by tireless efforts underground".

This is surely the sort of phrase that only the Japanese could have thought up. A small company that specialises in digital amplification, Flying Mole started out building little monoblocks for the professional world (which we once reviewed, without a great deal of enthusiasm) and has now started to make some rather distinctive integrated and pre/power designs.

The company was formed in November 2000 as a 'fabless' organisation, which means it doesn't manufacture but concentrates on planning, designing and selling. The people involved are a "group of engineers with an entrepreneurial spirit", quite a few of whom were formally with the Yamaha corporation.

This is how Flying Mole ended up with Ian Galloway, formerly Yamaha UK's managing director, as its distributor - without that connection the two would have been very unlikely to have hooked up.

The CA-S10 is the middle model of three domestic amplifiers. There's a single-input CA-S3 of tiny proportions at half the price and a pre/power combo with the same 100-watt output for twice the price.

Class D PWM

The compact nature of the rather attractive casework is a reflection of the digital internals - the Flying Moles use Class D PWM (pulse width modulation) technology and the CA-S10 has a variant called bi-phase PWM, which splits the signal prior to amplification.

It doesn't have a regular mains transformer, but relies on switching power supplies - one for each channel - making it one of the only dual-mono amps in its price range. This approach makes the amp extremely efficient compared to Class AB designs. It does get warm but not enough to warrant ventilation or heat sinking, and its power consumption at idle is a mere six watts - very green.

It is also beautifully built, the casework being of a standard that only the Japanese can produce at this price. All this power and hi-tech internals, combined with great casework, means that savings have to be made somewhere. In this instance, it's in the feature and input department - this is the first £1,000 integrated we've seen in a long while that doesn't offer remote operation.

It's also rather peculiar for having only three inputs and a single preamp output, which reflects its purist aspirations. Flying Mole is clearly trying to make the best-sounding amplifier it can for the price and given the degree to which it has succeeded you have to respect its approach.

While this is a 100-watt amplifier, it doesn't have the energy that one associates with that sort of power rating, and it couldn't comfortably drive our big B&W 802D loudspeakers. This is not the first time they have made the life of an 'affordable' amplifier difficult, and given the price differential it's an unlikely real-world partnership.

However, the pairing did stay together long enough to reveal the extraordinary levels of detail that the amp can produce. It achieves this as a result of having an uncannily clean sound, which makes alternatives sound electronic or mechanical by comparison. On the other hand, there is a slight fragility to the CA-S10's sound that discourages headbanging and leads your listening towards higher cultural ground. It will play loud with a suitably sensitive pair of speakers, but is devoid of the punch of a top-notch Class AB amplifier.

This is either because it doesn't have certain euphonic distortions that create the sensation of energy, which is presumably a result of the characteristics of regular power supplies and output devices combined, or because it is intrinsically less muscular and less able to drive real-world speaker loads.

Digital amps of yore have suffered from a far higher sensitivity to the load they are driving than their analogue counterparts, which can result in a sound that seems to lack dynamics. Given that early stumble when fighting above its weight with the B&W, we lined up a variety of different speakers to see how well this aeronautical lawn-breaker coped.

In the main, it handled things very well. The Mole was unfazed by Acoustic Energy's AE1, a compact, metal-driver speaker that's designed to take a lot of power. The amp extracted a solid and tight bass allied to a super-detailed midband and a well extended and remarkably clean top end, one which revelled in finer, high-resolution recordings such as David Wilczewski's Room in the Clouds SACD.

Decent tonal variety

Similarly, the more analytical qualities of ATC's SCM19 standmount did little to undermine the Mole's case. Here, the amp allowed the speaker to reveal decent tonal variety from a male choir and a thoroughly engaging sense of timing. It also did a good job of distracting from the analysis and letting us hear the music.

Even the aforementioned 802D, while being too much of a handful for the amp to sound like it was in full control, illustrated how the quality of high-frequency resolve provides definition right across the audio band. The bass got a little boomy and lacked the conviction and gravitas that more powerful sounding amplifiers can extract from this speaker, yet the Mole did show the shape of higher bass notes well and managed to provide plenty of timing clues.

But of all the speakers tested, the Living Voice OBX-R speaker proved to be a very sweet match. The smoothness of its treble fused perfectly with the Mole's crisp top end, delivering a result with real sonic integrity, transparency and precision.

The Flying Mole design reveals what can be achieved with digital amp technology if you leave out the bells and whistles and focus on the essence. This is a remarkably refined performer, even in the face of some seriously good amplifiers in and around the same price.

The only real limitation is in the dynamic range, and even here this is a relatively mild shortcoming. This is not an amplifier that plays loud, but neither does it 'sound' loud at any given volume level. Normally, perceptibly loud amplification suggests distortion, but the CA-S10 understates the sound more than usual.

Other low-distortion amps seem louder because they pull out dynamics significantly better, which suggests greater sensitivity to level variations. Such designs are rare, but not impossible to find at the Mole's price.

So it's a matter of picking your compromise - there's usually an alternative that does something a little better. But here it's pretty fundamental: do you want a refined and incredibly clean sound that demands a smooth, high-quality source, or do you want a ballsy sound with grunt that is better suited to rocking out?

If you think that the former could be for you, then this small but beautifully formed amp is a hard act to beat. So long as you don't want the bells and whistles, of course. Jason Kennedy