December
2018

Country of Origin

UK

Dream DAC

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, Fore Audio DAISy1, COS Engineering D1, Denafrips Terminator, Soundaware D300Ref,  AURALiC Vega 
Preamplifier: Nagra Classic, Wyred4Sound STP-SE Stage II, Vinnie Rossi LIO (AVT module)
Power & integrated amplifiers: Pass Labs XA30.8; FirstWatt SIT1 monos, F5, F6, F7; Goldmund/Job 225; Aura Note Premier; Wyred4Sound mINT; Nord Acoustics NC500 monos; LinnenberG Audio Liszt monos
Loudspeakers: Audio Physic Codex; Cube Audio Nenuphar; Albedo Audio Aptica; EnigmAcoustics Mythology 1; Boenicke Audio W5se; Zu Audio Druid V & VI & Submission; German Physiks HRS-120; Eversound Essence
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: TBA
Genesis. 2016's Moscow show had included a full system by Russia's then Wagner Audio. I'd already met designer Leonid Burcev in August 2015, Switzerland. Alas, the planned follow-up review of his Dream DAC delayed. Until now. In the intervening years, Etalon Sound (not be confused with Etalon Acoustics) was formed then subsequently restructured. At the 2018 HighEnd Munich show, Leonid had handed me a demo invite to Speed Matrix. It now referred to him as Master Leonardo. It talked of going "beyond R2R resistor networks and binary-weighted resistor DACs which are practically impossible to implement". As now exclusive OEM tech intended to license out to other builders, I couldn't actually review it. So I stopped these particular DAC dreams and went back to electrical sheep. Then on December 24th of all dates, Leonid's former secretary Ekaterina Snegur rekindled the Dream DAC. She explained how the delay had involved Leonid's departure from Etalon; then former partner Dmitry Katatonash [right] rebooting the company with new personnel and a focus on solid production/sales capabilities. The machine I'd been asked to test three years prior was finally a go. Its specifics read like Russia's echo to the Dutch tech of Metrum Acoustics: discrete R2R modules; variable voltage reference for non-lossy volume control which doesn't bit strip but instead alters the converter's voltage gain; fully balanced architecture from input to output; and a proprietary algorithm which splits each channel signal into independently processed bands which are gain-matched and reassembled at the output.

True balanced operation not only cancels distortion. It is claimed to remove one classic multi-bit converter weakness. "Our schematic resolves the zero-crossing flaw of all classic multi-bit converters with R2R matrix. At zero, all switches fire at once. This causes noticeable transient surges and high glitch. Since it occurs during the quietest moments of a recording when noise can't be masked by valid signal, it leads to audible distortion especially in the treble." Like Metrum, the split processing of the least/less significant bits, those which represent the lowest amplitude data, occurs at higher than normal levels before it is equalized prior to summing.

"Our algorithm fulfills the sonic potential of low-amplitude signals which otherwise render either distorted or obscured by noise. We realize this with a three-stage circuit which divides a single R2R array into three parts. Each is a separate converter processing its own signal fraction having an either low, medium or high level.

"The low-level signal is shaped by a chain of not 24 resistors like a conventional 24-bit R2R array but by just eight. This dramatically shortens the signal path. The digital code's least significant bits benefit from added gain before conversion and are returned to their normal level afterwards. This retrieves the lowest signal by stripping it of noise to maximize D/A extraction in the most important range of low-amplitude data."

Etalon's TUC or True USB Conversion module runs on proprietary FPGA code to generate an I²S output which syncs to a Russian military-spec femto clock that "functions better than most XMOS modules". It includes a signal buffer for jitter "below the sensitivity threshold of even the most accurate measuring devices". The resultant I²S signal feeds straight to the Super R2R circuit of 12 DACs (6 per channel, two per segment).

With their long view, Etalon also investigated cabling to determine that die-pulling raw conductors creates "asymmetrical properties when the wire conducts the positive and negative half waves of a signal". Their copper Litz arrays conductors of opposite directivity in parallel to enforce equal behaviour in either direction. Being consistent, this includes transformer windings, inductors and hookup wiring; and their own external cabling.

Their transformers use "a next-gen iron-based nano-crystalline alloy with extraordinary properties. They show a threefold decrease in core volume with considerable lessening of winding losses due to reduced turns ratio. Primary winding inductivity is up to 10 times that of silicon iron yet leakage inductance and inter-turn parasitic capacitances are far lower, leading to enhanced bandwidth."

Their 'symmetrized' Litz conductors show up not only in their transformers but also in exclusive 'double-ring' capacitors. Extending their investigations to speaker drivers, Etalon again mint their own in bell bronze baskets like Bernard Salabert championed for PHY HP; with Neomax magnets, parallel-wired multi-layer voice coils and suede suspensions. A full Etalon system for Western ears had premiered at the Hifi Deluxe 2017 show in parallel to the MOC event playing mostly classical music. It hadn't returned for 2018 whilst the company rebuilt under new management. However, they'd be back in force for Munich 2019. The timing of my review would double as advance notice.  … to be continued in February…