Country of Origin



Reviewer: Srajan Ebaen
Financial interests: click here
Main system: Sources: Retina 5K 27" iMac (4GHz quad-core with Turbo, 32GB RAM, 3TB FusionDrive, OSX Yosemite. iTunes 14.4), PureMusic 3.02, Audirvana 3, Qobuz, Tidal, Denafrips Terminator+ clock-synced to Soundaware D300Ref SD transport/USB reclocker; Preamp: Vinnie Rossi L2 Signature with WE VT52/300B or Elrog 50/300B; Power amps: LinnenberG Liszt monos; Headamps: Questyle CMA-800r monos; Phones: HifiMan Susvara; Loudspeakers: Audio Physic Codex; Cube Audio Nenuphar; Aurai Audio M1 [on loan]; Cables: Complete loom of Allnic Audio ZL; 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, LessLoss Firewall for loudspeakers, Furutech NCF Signal Boosters; Room: 4 x 6m with high gabled beam ceiling opening into 4 x 8m kitchen and 5 x 8m living room so no wall behind the listening chairs
2nd system: Source: Soundaware D100Pro SD transport; DAC/pre: Denafrips Terminator or COS Engineering D1; Amplifier: Bakoon AMP-13R or Crayon CFA-1.2; Loudspeakers: Acelec Model 1 w. Franck Tchang magnesium super tweeters, sound|kaos Vox 3awf, Zu Submission subwoofer; Power delivery: Furutech GTO 2D NCF; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan];  Sundry accessories: Audioquest Fog Lifters; Furutech NFC Clear Lines; Room: ~4x6m
Desktop system: Source: HP Z230 work station Win7/64; USB bridge: Audiobyte Hydra X+; Headamp: Kinki Studio Vision THR-1; Phones: Audeze LCD-XC on Forza Audio Lab cable; Powered speakers: Fram Audio Midi 120
Upstairs headfi system: Source: Soundaware A280 SD transport; Integrated amplifiers: Schiit Jotunheim R or Bakoon AMP-13R; Phones: Raal-Requisite SR1a, Audeze LCD-2, Final Sonorous X & D8000, HifiMan HE-1000
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: €4'500, add €900 for streaming module, €700 for phono module

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

1/3rd company owner Stephen Gong explained at RMAF 2019 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. 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 end price.

"The response at the Denver show was probably our best ever. Lots of people gave us two thumbs up. Everyone loved our sound. Some asked if we had show specials. All I had was one prototype."

Belonging to the general DAC/pre/headfi category of 3-in-1 multi kultis, the D10 adds slide-in options for phono and streaming. Packed to the gills, that hits 5-in-1 skills. Based on twin BurrBrown PCM 1792A converters, there's also analog relay-switched resistor-ladder volume 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 firm's familiar own linear-phase job. Headfi gets 2 x combo XLR3/6.3mm and 1 x XLR4. 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. The break-down chart between D1 and D10 puts it all on the page.