Reviewer: Srajan Ebaen
Financial interests: click here
Sources: 27" iMac with 5K Retina display, 4GHz quad-core engine with 4.4GHz turbo boost, 3TB Fusion Drive, 16GB SDRAM, OSX Yosemite, PureMusic 3.02, Tidal & Qobuz lossless streaming; Questyle QP1R [.aif], Apple iPod Classic 160GB [.aif], Astell& Kern AK100 modified by Red Wine Audio [.aif], Cambridge Audio iD100, Pro-Ject Dock Box S Digital, Pure i20
DACs: COS Engineering D1, Metrum Hex, AURALiC Vega, Aqua Hifi La Scala MkII, Fore Audio DAISy 1, Vinnie Rossi Lio
Preamplifiers: Nagra Jazz, Esoteric C-03, COS Engineering D1, Clones Audio AP1, Vinnie Rossi LIO [AVC option]
Power & integrated amplifiers: Pass Labs XA30.8, FirstWatt S1, F6; Crayon Audio CFA-1.2; Goldmund Job 225; Gato Audio DIA-250; Aura Note Premier; Wyred4Sound mINT; April Music Stello S100 MkII, Vinnie Rossi Lio, AURALiC Merak [on loan]
Loudspeakers: EnigmAcoustics M1, Albedo Audio Aptica, soundkaos Wave 40, Sounddeco Sigma 2; Zu Audio Submission; German Physiks HRS-120, Eversound Essence w. TR-3D subwoofer
Cables: Complete loom of Zu Event; Black Cat Cable redlevel Lupo; Ocellia OCC power cord loom [on loan], KingRex uArt double-header USB; Tombo Trøn S/PDIF; van den Hul AES/EBU; AudioQuest Diamond glass-fibre Toslink
Power delivery: Vibex Granada/Alhambra on all components
Equipment rack: Artesania Audio Exoteryc double-wide 3-tier with optional glass shelves, Krion amp shelf
Sundry accessories: Acoustic System resonators, two Verictum Silver X Block (EMI/RFI traps for component chassis) on preamp and amp
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: $6'600/10'000 SE/XLR Edition; $15'000/$20'000 SE/XLR Signature

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 kinfolk 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, TotalDAC from France - and today's Rockna Audio. Like my favourite accordeon player Roberto de Brasov, Rockna stem from Romania. Their Wavedream converter started life driving MSB modules like the Bulgarian Thrax and Swiss ReQuest Beast still do. But today's Wavedream runs on proprietary tech. Over the years, Rockna's engineering rock Nicolae has provided OEM/ODM assistance to Audio Mirror, Acoustic Precision, Fase, Jadis, Nonsolomusica, PS Audio with their PerfectWave transport, Wadia, Goldmund and even MSB. Whilst his name might not ring a bell, Rockna Audio have been around for 15 years.

Where Rockna are the no-holds-barred high-end division, Audiobyte are their more affordable spin off. Audiobyte's tidy catalogue is currently three deep: a D/D converter aka USB bridge; an optional ultracap'd linear power supply for it; and a 3-for-1. That's a digital pre/headfi amp and DAC called Black Dragon. It's the replacement for the earlier Silver Dragon. Befitting Audiobyte's Rockna DNA—hold tight to your wig because now we'll rattle off lotsa tech—there's FPGA-based 500MHz sampling, 15 DPS-core filtering, sub pico-second reclocking and 127-step precision volume control with memory function. D/A conversion is via dual Asahi Kasei AK4396 chips for balanced mono processing. The Black Dragon eschews all analogue inputs to be purely digital via USB, 75Ω coax, 110Ω AES/EBU, Toslink and I²S over HDMI. Class A fully discrete zero-feedback outputs come in triplicate: 10vpp RCA, 20vpp XLR, 800mW/32Ω 6.3mm. Sample rate support is up to 96kHz for optical, 192kHz for S/PDIF and 384kHz/DSD128 for USB/I²S. Bit depth is 24 bit for all inputs except USB/I²S which accept 32 bits. Finally there's remote control and a red-on-black dot matrix display. The custom FIR filter can be defeated but is recommended to stay on. It eliminates pre-ringing. Hence the bold capitalized command. Stay warm. Keep yer fur on.

, that I did fib in Photoshop. It really says FIR ON. But where's the fun in that? A fur filter sounds far more cozy. And if steeper pricing gets you frosty, now is the time to engage your own thermal filter—heat flash or power surge as women say—as we transition to Rockna Audio and their up to $20'000 Wavedream DAC. This intro simply let you know that a $2'100 Rockna-derivative DAC is available too at 1/10th the wallet pain.

With a last name like Jitaru, Nicolae is genetically wired to feel all jittery about jitter. The WaveDream DAC not only gets a proprietary USB solution—not a generic M2Tech, XMOS, Amanero & Co transceiver module—but also selectable digital filters. Those were written by Jitariu's team. Wig time again. These filters exploit 15 GMACS of processing power from 58 DSP blocks and "avoid standard Nyquist rate filters" in favour of "an advanced 2000-tap convolution filter created from a Parks-McClellan equiripple combined with a raised cosine type". I have no idea what that means.

Original Wavedream with MSB Platinum modules

Even Nucu's Femtovox clocking scheme is different. "The heart of the WaveDream clocking system is a digitally programmable low-jitter clock. Its precision is set by a 38-bit control word which gives an accuracy of <1ppb (parts per billion). This clock generation creates a very low jitter of 0.3ps or 300fs on any input sample rate. In absolute terms there are claims of lower jitter figures on the market which can be obtained only by using oven-controlled crystals at single frequencies. With sample rates varying from 44.1 to 384kHz, it’s unlikely that a DAC can work with a single master-clock frequency unless it uses an ASRC with its own set of problems. Our digitally controlled clock allows bit-transparent operation without the smearing caused by an ASRC block. But the master-clock generation technique isn’t all. To properly adjust the digitally controlled oscillator frequency, our system measures the incoming sample rate with high accuracy. Whilst that could simply program the DCO, we use a complex algorithm that takes care of the real frequency that's written in real-time to the DCO. The algorithm keeps frequency variations to a minimum to yield a fixed frequency in the short term and to track source frequency deviations over the long term. The resulting loop corner frequency of the system is as low as 0.5Hz." All incoming data of 44.1kHz or multiples thereof upsample to 705.6kHz. 48kHz and its multiples arrive at 768kHz. A-weighted dynamic range is 132dB, S/NR 132dB, output impedance 0.5Ω. Asynchronous input reception occurs at 560MHz sampling and the "memory-based digital-domain PLL" operates at 300fs jitter. Mathematical precision is 68-bit integer, the volume control is a 256-step custom multiplier array over 0.5dB increments implemented as quad 63-bit DSP inside the FPGA. Selectable dither is "4-bit Gaussian ultrasonic". The 128x65 yellow Oled display is dimmable over 8 steps, the firmware is USB upgradeable—which by altering the FPGA coding actually upgrades hardware—and there's remote control. The user can invert phase, select between linear, minimum and hybrid filters, activate the dither generator and alter the digital PLL settings between local clock and clock stream. Phew. Have we reached brain overload by now?

Current Wavedream with Rockna RD-0 modules in fully balanced guise