COS D1 digital converter/preamplifier

Solid-state preamplifiers,
Digital-to-analog converters
COS Engineering D1

Those looking for a line level output from the D1 will find that the only way to achieve this is to set the volume control to maximum, illuminating all the lights underneath the control. Once you select an input you are left with a single small white LED that flashes if it’s not locked to a signal. Controversially the left and right channel in and outputs are inverted so that red is on top but even an experienced reviewer can figure out stuff like that given time! It comes with a set of impressive looking spike feet that screw onto the base but I have never been keen on the sound of spikes on glass shelves (as found on my Townshend Seismic stand) so left them off and used soft pucks of the large and rubbery variety. The resulting sound had remarkable delicacy and finesse. For example, ‘La Cancion Sophia’ is one of the quieter pieces from Corea, Clarke, and White’s Forever [Concorde Records] and the COS revealed just how low its noise floor is by unveiling oodles of fine detail at the quieter end of the spectrum, with strong imaging from the piano, bowed double bass, and cymbals, with the latter exhibiting greater reverb than you usually hear.

This was followed by Barenboim’s take on the Vivace of the ‘7th Symphony’ [Beethoven for All, Symphony No. 7 in A, Op. 92, 24/96, Decca]. Here the fine detail was equally well served, but the slow build up proved even more riveting. The weight of the plucked basses low down in the mix and the way that Barenboim delivers the tension and release of the piece shows that the COS can do dynamic range as well as low level detail. The two are of course facets of the same quality; the quieter a system is the more scope there is for dynamic expression. This also illuminates the fact that the COS does not indicate the sample rate of the incoming signal; I guess with high res, you are always using a streamed source of some form and such details should be available elsewhere, but it’s nice to have confirmation that it’s getting to the DAC.

I had a Bryston BD3 DAC on hand during the COS’s tenure and so made a few comparisons with a coaxial source. This revealed that the COS is a sweeter sounding, softer edged converter that gives away some ground in terms of the leading edge definition that makes detail more easily discerned. The Bryston also reproduces more of the acoustic scale of the recording. But these are chalk and cheese converters, the COS having a smoothness and finesse that those of a more romantic bent would likely prefer to the visceral clarity of the Bryston. It did make me wonder about the feet though (!), so big spikes were installed and the D1 sat upon small Bluehorizon damped receptors. This proved to be a better approach than the heavily damped pucks and injected a stronger sense of timing without undermining the subtlety of the DAC. Now it could do immediacy with greater effect and delivered more expansive soundstaging; in fact with better recordings there was acres of space and depth to enjoy.

I also contrasted it with the Primare PRE60 reviewed elsewhere in this issue – a more likely competitor given its functionality and price. The PRE60 also upped the ante in terms of power and definition, adding stronger dynamics in the process when driven by a USB source. The COS on the other hand sounds more composed and more interested in savouring the moment than riding the leading edge. The sax on Herbie Hancock’s version of ‘Ain’t Necessarily So’ [Gershwin’s World, Herbie Hancock, Verve] has great tone; it positively oozes out into the room with excellent stereo solidity. The tempo is steady and seems very natural and when the next piece comes on Joni Mitchell’s voice is beautiful, full of expression and nuance, fully reflecting the nature of Mitchell’s sound on one of her last recordings.

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