Country of Origin



Reviewer: Srajan Ebaen
Financial interests: click here
Sources: Retina 5K 27" iMac (4GHz quad-core with Turbo boost, 32GB RAM, 3TB FusionDrive, OSX Yosemite. iTunes 14.4), PureMusic 3.02, Audirvana 3, Qobuz Hifi, Tidal Hifi, COS Engineering D1, Denafrips Terminator, Soundaware D300Ref,  AURALiC Vega, Jay's Audio CDT 2 MkII & DAC-2 SE
Preamplifier: Vinnie Rossi L2 Signature with WE 300B or Elrog ER50; Nagra Classic, Wyred4Sound STP-SE Stage II, Vinnie Rossi LIO (AVT module)
Power & integrated amplifiers: Pass Labs XA30.8; FirstWatt SIT1 monos, SIT-3, F5, F6, F7; Goldmund/Job 225; Aura Note Premier; Wyred4Sound mINT; Nord Acoustics NC500 monos; LinnenberG Audio Liszt monos; SAG AIO; Bakoon AMP-13R
Loudspeakers: Audio Physic Codex; Cube Audio Nenuphar; Kroma Audio Mimí; Albedo Audio Aptica; EnigmAcoustics Mythology 1; Boenicke Audio W5se; Zu Audio Druid V & VI & Submission; German Physiks HRS-120; Eversound Essence; Fram Midi 150; sound|kaos Vox 3f [on review]
Cables: Complete loom of Allnic Audio ZL3000 and Zu Event; KingRex uArt, Zu and LightHarmonic LightSpeed double-header USB cables; Tombo Trøn S/PDIF; van den Hul AES/EBU; AudioQuest Diamond glass-fibre Toslink; Black Cat Cable redlevel Lupo; Ocellia OCC Silver
Power delivery: Vibex Granada/Alhambra on all source components, Vibex One 11R on amps/sub
Equipment rack: Artesania Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc Krion and glass amp stands 
Sundry accessories: Acoustic System resonators
Room: 4 x 6m with high gabled beam ceiling opening into 4 x 8m kitchen and 5 x 8m living room, hence no wall behind the listening chairs
Review component retail: €5'000, add €1'000 for streaming module, €800 for phono module

BeCOS. Should you wonder why now the new COS Engineering D10, it's because the original D1 flag ship, whilst winning many awards and putting the firm solidly on the map, also made for a harder €9'000 sell from a then new Taiwanese outfit who hadn't anticipated our industry's deep margin structures.

1/3rd company owner Stephen Gong shown at RMAF 2019 in Denver explained that "the D10 isn't just a D1 in simpler threads. It's a quite different beast. We needed a seriously short haircut on build costs but still wanted to push the sound further, too. The simpler housing remains in full aluminium on the outside but reduces our original very high machine-shop fees with associated chassis rejects by 60%. For this circuit, parts cost is down by 20% which together with the enclosure savings helped us create a very attractive retail price.

"The response at this year's Denver show was probably the best we ever had. Lots of people gave us two thumbs up. Everyone loved our sound. Some asked if we had show specials. All I had with me was one prototype. Hopefully we can release the D10 in November. But that'll be a very tough order."

Belonging to the DAC/preamp/headfi category of multi-tasking 3-in-1, the D10 shocks by still adding slide-in streamer and phono options. Packed to the gills, that hits rare 5-in-1 dominion. Based on twin BurrBrown PCM 1792A converters, there's also an analog relay-switched resistor-ladder volume control from -64 to +6dB in 0.5dB steps. That supports purist RCA and XLR analog inputs without first converting them to digital. For digits, there are asynchronous USB 2.0, BNC, AES/EBU and Toslink plus a new I²S over HDMI port. Data support goes to 24/192 PCM and DSD128 DoP. The digital filter is the company's familiar own linear-phase job.

Headfi gets two unbalanced inputs and twin XLR3 plus one XLR4 port. The PSU runs dual toroidal transformers to keep analog and digital circuit feeds separate.

The optional streaming module with 10/100 Base-T WiFi and UPnP/DLNA support will be Roon ready and support Tidal, Deezer, Qobuz and Spotify plus MQA Core for 2 x decoding without rendering. The optional phono module will have 3-stage gain up to 60dB and 0-750pF loading in 50pF steps. This break-down chart between D1 and D10 puts it all on one simple page.

In short, the D10 piles on the features, then seriously slashes the price. Mechanically, the housing morphs from solid aluminium for the D1 to a two-layer structure of inner steel hull with front/back partition for digital and analog all disguised behind sand-blasted thin aluminium dress panels. The white Oled display with large readout of volume, input, sample rate and signal lock gets a resolution upgrade yet the D1's metal remote control stays, then packaging scales up to this custom flight case.

In the front, dual combo 6.3mm/XLR3 ports surround the XLR4 for headfi.

It felt predestined.

With the D10, COS Engineering would open many dealer doors to increase their global footprint. Making the add-on modules user-fittable without dealer intervention or return to Taiwan was smart and saves coin for those who don't want these features or mean to build out their deck in stages as finances allow.

Cos célèbre?

We'll find out about performance when first review samples drop. With a D1 and an H1 in inventory both purchased after their respective assignments, I'd have the two very units which the D10 rolls into one to report on whether COS indeed managed to push their sound higher still.

As to everything else, I thought that things already added up in a big way for this new beast from the East. It packs a real dream team of can-do under one smartly styled hood without visible fasteners or frills. What's not to like?

… to be continued…