Code: proprietary. PureMusic's setup window identified the COS D2 by name, not as a generic XMOS/Amanero/hiFace USB transceiver. It showed up 384kHz and hog mode compliance. Where MQA marketeers paint their digital filter as best, more than one digital designer who laboured hard to write his own disagrees. With custom code originally written for the D1, the D2 too prefers to run its own. That omits the silly blue light and also bypasses what BurrBrown/TI use on the D2's two chips.


As a happy owner of the D1, it was obviously obligatory to instigate she-said-he-said sibling dispute. For the full measure, it meant balanced direct drive into our LinnenberG Allegro monos fronting our white Audio Physic Codex. With its ¼dB display, smaller youngster immediately upstaged bigger elder on precisely repeatable levels. Here the D1's stylish white LED smile plays it like a one-handed watch. It shows approximate time in 5-minute increments. The D2 was the RF-controlled digital watch with a 1/10th of a second display. As a purely functional difference, it as yet said nothing of sound. In preamp not fixed-gain DAC mode, it did say that the D2 was rather more purpose designed. Being smaller and far less costly too, the D2 entered this contest with a 3-point advantage. I felt that the D1 would have to sonically dominate in a quite obvious way to redress that balance.


Phrase: uncommon. As the Irish Times writer Sergei Aksyonov put it in a recent political essay, "...apricot blossom already dusts the sun-dappled fields of Bakhchisarai but Safinar Dzhemilev is in no mood to savour springtime in the ancient capital." From this we pick the poetic turn of phrase sun dappled. Very different from the previously reviewed full-tube HQ9038 DAC, the D2-fronted system sounded light-filled and lithe. Fully elucidated yet tangibly elegant, its treatment of the treble anchored the reading in sun light. Usually for 'anchor' we call out earthiness and potent bass because the visual connotes a downward force whose reference point is well below the surface. By the same logic, we call the opposite presentation suspended or floating. After all, a top-down reference point is above the head. As my best attempt to describe the D2's primary effect, I have cross-referenced anchor with light. This counters suspicious notions that it felt lightweight or unduly ephemeral and wispy as might be expected for such perspectives.


From a loudspeaker angle, we might invoke an unusually clear yet refined tweeter like perhaps a Raal ribbon, superior Heil derivative or diamond driver. Their contributions are never forward, bright, steely or otherwise dominant in any forceful showy fashion. Quite the opposite. It is the very absence of such artifice which defines them. Yet the resultant quality remains all pervasive like the firmament domes across any big-sky country. When electronics and recordings allow, this invariably manifests in lengthy decays and very specific imaging with excellent recovery of recorded ambiance. In our hardware collection, think EnigmAcoustics Mythology 1 monitor with Sopranino electret super tweeter. The D2 was that M1 in DAC guise. Properly grounded and decidedly not tipped up, to our combined system sound it still made a very similar electrostatic super-tweeter contribution. Sun dappled. Elegant and most informative without feeling at all explicit or pornographic. This went beyond the usual avoidance of complications like eliminating a separate preamp and its cabling. This went beyond the distortion-canceling benefits of balanced signal processing when other fully balanced chains sound different. As a guess, I'll point at two prospective causes: the chosen Burr-Brown chips and their tuning; and the expertly integrated switch-mode power supply.

As we saw in the earlier photos, for our D/A + analog attenuation purposes today, a very compact ±15VDC/500mA SMPS is sufficient. Properly shielded and filtered, this design choice strikes me as the most likely cause for those sonic aspects we might here group under refined speed. It's when speed isn't the primary concern of going nowhere fast. It's when speed is merely the enabler of fleet-footed refinement. Linn and Chord have championed this approach for decades. Even Nagra use variations on switching supplies in certain of their machines. Here it eliminates the two toroids of the D1, its rectifier and assorted filtering/smoothing caps. Quick and very quiet, with a panoramic sonic vista of excellent depth of field and that ever-present "big sky" treble finesse... the D2's score card was unmistakable. With that sorted, it was time to invoke that sibling rivalry. But first, a quick vocabulary test.
Buffer engaged, AES/EBU input with signal lock, normal volume in our room at about 40dB down from the full 4V balanced outputs.