Sound quality

The frequency range covered by the cM9 is 30hz – 50khz at 6dB and is more tightly specified at 56hz – 22khz +/-3dB. We haven't see the response plot, but most of it probably lies below the line, between 0 and -3dB, with the output holding within 2dB over a ten degree vertical arc and 60 degrees horizontally.

Impedance is nominally eight ohms, but dips to three ohms, which means it is best thought of as a six-ohm load, though the 89dB sensitivity means that you shouldn't need too much power to get a good result.

The main test amplifier was a Krell fBi, which can deliver 300 watts per channel without breaking a sweat, which is more than sufficient horsepower for any reasonable use. But in a brief outing with a high-quality 50-watt integrated amp, the Denon PMA-SA1, even this reduced power level was sufficient to propel the CM9 a long way, with no danger of hitting the end stops in a room which is more than eleven meters long.

This is not a hard loudspeaker to drive. You wouldn't expect a modern Bowers and Wilkins to be far from tonally neutral and the CM9 doesn't disappoint. This is palpably a very accurate loudspeaker with a full, but well contained bass and a treble quality that has come some way from the occasionally thin, edgy quality of some earlier generations of metal dome tweeters.

It's not that the company's speakers were particularly edgy, but there was something about their tweeters and the slightly antiseptic way the treble was framed as a whole, that somehow underlined the high frequency output. it seems that the process of continual refinement really has delivered the goods and the result is a speaker that is palpably better integrated and that sounds less loudspeaker-like – more transparent if you will.

In part, this is because it is no longer possible with this loudspeaker to hear the treble as a separate entity, independently of the bass and the midrange. The Kevlar FST midrange unit plays a part here by boosting energy in the middle and upper midband, the region just below where the tweeter takes over.

The result is a loudspeaker that is obviously smooth and in control, but is also capable of delivering real surprises when the occasion demands, one of which was playing a CD of wind music, a new Naxos title called Passaggi, which is scheduled for review in choice cuts next month.

The exotic woodwind textures featured on this disc were beautifully handled, with a palpable feel of the player's breath energising the instruments. In track eight (part II of Nebojsa Zivkovic's Tales from the centre of the earth) the music has a tremendously exciting rhythmic pulse and here the CM9 brings a powerfully tactile quality and bite to the proceedings. We did notice a degree of interaction between the speakers and the amplifiers though, which in the worst case tends to induce a small, but noticeable amount of colouration and a degree of boxiness in the midrange.

The bass is perceptibly warm when we used it without the foam ring or plug in the reflex port (they're supplied separately, with the advice to use them if the speakers are placed close to the wall behind). Generally the bass breathes better and gives a greater impression of differentiation in the depth plane, if some space is left behind the speaker and the foam is not used.

This is a first-rate newcomer, easier and more relaxing than some previous Bowers and Wilkins, with a more expansive sound and a better-integrated treble. it is realistically priced, and beautifully finished, but take some care over set up.

The speaker does offer a wide listening window, which is not just limited to a point immediately between the two speakers. It is quite transparent, though, and should be used with clean-sounding electronics, if you don't want to excite the slight residual boxiness identified above.

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