Country of Origin



Reviewer: Srajan Ebaen
Financial interests: click here
Main system: 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, Denafrips Terminator, Soundaware D300Ref SD transport & USB bridge; Preamplifier: Vinnie Rossi L2 Signature with WE VT52/300B or Elrog 50/300B; Power amplifiers: LinnenberG Audio Liszt monos; Headphone amp: Kinki Studio; Headphones: Final D8000; Loudspeakers: Audio Physic Codex; Cube Audio Nenuphar; Aurai Audio M1 [on loan]; Cables: Complete loom of Allnic Audio ZL3000; Power delivery: Vibex Granada/Alhambra on all source components, Vibex One 11R on amps, LessLoss C-MARC Entropic cords between wall and conditioners; Equipment rack: Artesanía 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
Second system: Source: Soundaware D100Pro SD transport; DAC/pre: COS Engineering D1; Amplifier: Bakoon AMP-13R; Loudspeakers: Acelec Model One w. Franck Tchang magnesium 360° super tweeters, Zu Submission subwoofer, LessLoss Firewall for Loudspeakers; Power delivery: Puritan Audio Lab PSM-156; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan]; Room: ~4x6m
Desktop system: Source: HP Z230 work station Win7/64; USB bridge: Audiobyte Hydra X+; Headphone amp: COS Engineering H1; Headphones: Audeze LCD-XC; Powered speakers: Fram Audio Midi 150
Upstairs headfi system: Source: Soundaware A280 SD transport; DAC: Auralic Vega; Integrated amplifier: Schiit Jotunheim R; Headphones: Raal-Requisite SR1a
2-channel video system: 
Source: Oppo BDP-105; DAC: Kinki Studio; Preamp: Wyred4Sound STP-SE II; Power amp: Pass Labs XA-30.8; Loudspeakers: German Physiks HRS-120; Room: ~6x4m
Review component retail: €5'000, add €1'000 for streaming module, €800 for phono module

BeCOS. Should you wonder why the new COS Engineering D10, it's because the original D1 flagship, whilst winning awards and putting the firm on the map, also made for a harder €9'000 sell from a then new Taiwanese outfit.

1/3rd company owner Stephen Gong shown at RMAF 2019 explained that "the D10 isn't just a D1 in simpler threads. It's quite a different beast. We needed a seriously short haircut on build costs yet still wanted to push the sound further. 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 set a very attractive retail price.

"The response at the 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."

Belonging to the general DAC/preamp/headfi category of multi-tasking 3-in-1, the D10 shocks by adding slide-in streamer/phono options. Packed to the gills, that hits rare 5-in-1 expertise. 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 is Roon ready and does Tidal, Deezer, Qobuz and Spotify plus MQA Core for 2 x decoding without rendering. The optional phono module has 3-stage gain up to 60dB and 0-750pF loading in 50pF steps via dip switches on the rear panel. This break-down chart between D1 and D10 puts it all on one simple page.