Headphones

The processor also handles the volume control, the system claimed to 'dramatically outperform all the pure-analogue, stepped attenuators we've evaluated', while the output stage uses discrete Class A FET amplification. Analogue inputs are digitised using a 384kHz/32-bit ADC from AKM, the processor handling digital inputs at up to 384kHz/32-bit and DSD128, the latter transferred via DoP.

Pushing Up The Levels
I stuck with digital inputs for almost all my listening, simply because that's how the majority of my music is, and putting it through a DAC/ADC/DAC chain – as I did by running my usual Naim NDS through the analogue inputs – really didn't seem to make much sense in assessing the product.

I have to admit that initial impressions of the M1 weren't too favourable, but this was nothing to do with the sound – which is all about thrilling dynamics and presence – but rather concerned the comfort. From new, the headphones seemed very tight and rigid, with a heavy clamping action on the head. Listening at low levels also showed quite a lot of mechanical noise transmission coming from the cable to the ears, and some creakiness from the structure as I adjusted the fit on my head.

However, over extended listening both discomfort and noise seemed to abate, the former as the headphones seemed to loosen up a bit, the latter as I was clearly enjoying them so much that I pushed the levels further up the scale.

Steinway Presence
Since it's an open-backed design, the M1 headphones let quite a lot of sound both in and out, so are really best suited for 'anti-social headphone listening' where one needs neither to keep the world out nor the music from disturbing others – but the reward for that is a sound of exceptional freedom and airiness, a long way from the 'shut in' headphone norm.

With an eye to the antecedents of the design, I opened critical listening with Tina Margareta Nilssen's Appassionata set of piano music by Beethoven, Grieg and the Norwegian composer Signe Lund [2L 2L-142; DSD128 download]. Here I was struck by both the weight of the Steinway and its delicacy, plus the way the church acoustic in which it was recorded adds distant ambience without ever becoming intrusive. A very real instrument in a remarkably convincing acoustic – that's what the Sonoma M1 system was delivering, and nowhere more so than with Lund's 'Cinq Morceaux'. Lund (1868-1950) is a composer unfamiliar to me, but clearly her work is worth further exploration.

Entirely Immersive
That sense of an intimate connection with the performance was equally apparent with something rather different – Van Morrison's 'standards' set, Versatile [Exile/Caroline International 60256705335; 96kHz/24-bit]. Here the M1 did a fine job with the close-up view of the singer's voice, delivering all its detail and texture in front of a band that's clearly entirely at ease and working well together.

I have to admit to a shudder at the thought of yet another album of music's old chestnuts – they seem to be all the go at the moment, and most are pretty toe-curling – but The Man manages to pull it off thanks to sheer musicianship, which is served well by the wide-open view these headphones deliver.

The Sonoma system rocks, too, with the dense Euro-rock of David Bowie's Heroes in its recent 192kHz/24-bit remastering [HDtracks] benefiting from the excellent insight on offer. It's impressive how these headphones can punch out fast, crisp rhythms, while the bleak instrumental layers of the likes of 'Sense Of Doubt' are at once laid bare and entirely immersive. Most striking is the really rich and grumbling bass these headphones can deliver, and the way this integrates completely with a midband that's forthright without ever becoming overly strident. The treble, too, is as remarkable for its extension and openness as it is for its sweetness and purity.

Yes, that makes the M1 something of a 'take no prisoners' enterprise, in that it's ruthlessly revealing of poor production or low-resolution transfers – as I guess one might expect given the system's provenance. But what was striking was just how good the headphones could sound when one of my sources was nothing fancier than a £200 used Mac mini treated to a bit of fettling. As an exemplar of 'source last' thinking, which suggests that all will be well if the computer data is delivered cleanly, and the DAC and headphone/amp system make the difference, the review set-up was highly persuasive.

Hi-Fi News Verdict
You've got to be pretty fanatical about your headphone listening to drop £5k on a pair of cans, but if you are and you do, then the Sonoma M1 will reward you with a sound of spine-tingling clarity and dynamic ability, allied to an open spaciousness that makes almost any well-produced album an enthralling experience. Add in the sense of luxury of the whole enterprise and you have a very special system indeed.