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 12.2), PureMusic 3.02, Qobuz Hifi, Tidal Hifi, Fore Audio DAISy1, COS Engineering D1, Aqua Hifi La Scala MkII, Metrum Hex, AURALiC Vega,
Preamplifier: Nagra Jazz, Esoteric C-03, Vinnie Rossi LIO (AVC module)
Power & integrated amplifiers: Pass Labs XA30.8; FirstWatt SIT1, F5, F6, F7; S.A.Lab Blackbird SE; Crayon Audio CFA-1.2; Goldmund Job 225; Gato Audio DIA-250; Aura Note Premier; Wyred4Sound mINT; AURALiC Merak [on loan]
Loudspeakers: Albedo Audio Aptica; EnigmAcoustics Mythology 1; soundkaos Wave 40; Boenicke Audio W5se; Zu Audio Submission; German Physiks HRS-120; Eversound Essence
Cables: Complete loom of 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; Arkana Research XLR/RCA and speaker cables [on loan]; Sablon Audio Petit Corona power cords [on loan], Black Cat Cable Lupo
Power delivery: Vibex Granada/Alhambra on all components, 5m cords to amp/s + sub
Equipment rack: Artesania Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc Krion and glass amp stands [on loan]
Sundry accessories: Acoustic System resonators
Room: Irregularly shaped 9.5 x 10m open floor plan with additional 2nd-floor loft; wood-paneled sloping ceiling; parquet flooring; lots of non-parallel surfaces (pictorial tour here)
Review component retail in Europe: €13'500 incl. VAT, add €1'000 for server/streamer board for the standard version; €13'500 for tube version (no server/streamer option)

Pushing the envelope. The d1-six is Vincent Brient's most ambitious one-box DAC to date though technically, it arrives with an outboard power supply. But that's a little thing, not the full-size case as it is for TotalDAC's dual-chassis models. Tech trickling down from the d1-twelve and d1-server here result in six channels of discrete R2R ladders over the four which appear in the d1-dual. Hence the d1-six nomenclature. Its standard output stage is transistor updated over his earlier efforts and optimized for all three outputs: XLR, RCA and 6.3mm headfi. This new French sixy sauce can be retroactively poured over all the d1 models. To continue with modularity, the d1-six can also take a Roon-ready server/streamer board for direct network use (local or cloud-based files); a 2/3/4-way active crossover custom-tuned to a specific speaker; a 5Vrms instead of 2.5Vrms output option particularly useful perhaps for the rear-mounted 6.3mm port; a bass boost; a BNC instead of coax input; a silver instead of black fascia; and come with a tube output stage as reviewed.

If you've paid any attention to DAC development over the past few years, you've noted the vast majority of Delta-Sigma users; a far smaller group of classic multi-bit contrarians who either harvest dwindling inventories of 16-bit NOS chips (AudioNote UK, AMR), exploit industrial/military current silicon (Schiit) or mint their own ICs (Metrum); and the even smaller FPGA brigade who code programmable chips to do their bidding, sometimes in PCM mode (Chord), sometimes in DSD mode (Meitner, Playback Design, PS Audio). A fourth group of refusniks to fashion and current trending are spiritual kin to the classic multi-bit contrarians. They however execute their R2R ladders with discrete resistor arrays, not integrated chips. To this crew belong MSB from the US, S.A. Lab and Wagner Audio from Russia, LessLoss from Lithuania, Rockna Audio from Romania and today's TotalDAC from France. Where the integretniks achieve their ladder schemes stuffed into commercial chips the size of a stamp or thumb nail—they might still multi-parallel those—the diskretniks of Vincent's type have to precision match hundreds of top-shelf resistors, then use glue logic via FPGA to switch them all in the desired manner. Theirs is the difference between a prefab house and one that's built by hand, one tiny brick at a time.

Not only is the raw parts cost far higher, so is the involved labour. One thus doesn't see discrete R2R converters in the lower price ranges. How many bricks in the d1-six's wall, you want to know? 300, of the 0.01% tolerance VAR bulk metal foil Vishay sort. If you wonder why Vincent bothers bricking it to such an extreme extent for what after all is a two not multi-channel affair, consider the noise floor of the FFT graph (linear view so the scale starts at 0Hz at the very left). It's spectacularly low. Inside the same rakish box sits a 192kHz asynchronous XMOS transceiver for USB. Optionally, DSD via the DoP protocol can be enabled for USB, AES/EBU and the S/PDIF inputs. Also inside is a custom clock with FIFO memory to reduce jitter; a remote-selectable NOS compensation filter; and a class A discrete solid-state output stage. The case work combines aluminium with PMMA which is polymethylmetahcrylate or plexiglas to us natives. All the electronic bits and bobs enjoy a solid footing on that "massive pure copper anti-resonance plate". Dimensions are 11 x 36 x 29cm HxWxD, with 6.5 x 12.2 x 18cm for the power supply. Weight of the lot is a very benign 7kg.

To throw another name of pedigree into Vincent's already much accoladed tech, Nagra Audio a few years back were in serious negotiations to license his IP. That's before they finally opted for a course correction into an OEM Andreas Koch module to play the "everything DSD" card instead. But it's certainly noteworthy that our Swiss were impressed enough by TotalDAC's approach to consider adopting their digital-domain expertise for their own machines. On Vincent's site, you'll find more background information on him, his company and present listening rooms to paint the full picture. The final detail is the pair of ECC82/12AU7 in the d1-six-tube as the very latest and newest from our productive Frenchman. His envelope should be bursting right about... now!