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 3.01, Tidal & Qobuz lossless streaming, COS Engineering D1, AURALiC Vega, Aqua Hifi Formula, Fore Audio DAISy 1, Apple iPod Classic 160GB (AIFF), Astell& Kern AK100 modified by Red Wine Audio, Cambridge Audio iD100, Pro-Ject Dock Box S Digital, Pure i20, Questyle QP1R, Soundaware D100 Pro Deluxe
Preamplifier: Nagra Jazz, Esoteric C-03, Vinnie Rossi LIO (AVC module), COS Engineering D1, Wyred4Sound STP-SE II, Octave HP700 [on review]
Power & integrated amplifiers: Pass Labs XA30.8; FirstWatt SIT1, F5, F6, F7; Crayon Audio CFA-1.2; Goldmund Job 225; Aura Note Premier; Wyred4Sound mINT; Nord Acoustics UP SE NC500MB; AURALiC Merak [on loan]; Octave RE320 [on review]
Loudspeakers: Albedo Audio Aptica; EnigmAcoustics Mythology 1; Sounddeco Sigma 2; soundkaos Wave 40; Boenicke Audio W5se; Zu Audio Druid V & Submission; German Physiks HRS-120; Eversound Essence; Rethm Bhaava [on loan], Vivid Audio Giya G4 [on review]
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 redlevel 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: Rectangular 5.5 x 15m open floor plan with two-storey gabled ceiling, wood-sleeved steel trusses and stone-over-concrete flooring
Review component retail: €6'950

Cess Ruijtenberg. "It's easy to see how the Adagio is part of the same family as our Pavane yet under the hood we optimized it to excel as a preamplifier. Compared to the Pavane, we made several changes to insure that performance of the volume control remained constant across its range. Since we alter the reference voltage of the converters to change volume, we needed the very best performance from them. Therefore we drive them almost to their limits for the lowest distortion and best S/N ratio. We also changed the DAC ONE module of the Pavane to the newer DAC TWO. As you'll remember, we used an FPGA to split up the 24-bit domain into two streams, each fed to a single DAC One module. Afterwards we summed these streams to get back the full analog signal with improved low-level linearity.


"I'd always wanted to get this process under the hood of just one module. In other words, take two of the DAC ONE modules plus their external FPGA, then put them in the small housing we already used. First steps were taken under a microscope and successful. We aced this during the spring of 2016 but a lot of effort then went into optimizing our test facilities. We must load each DAC with the algorithm and test it at the same time. Because we like to watch for consistent performance, production capacity was limited. For instance, we see the effect of pollution on very low levels due to solder residue. It's one more reason why one should never build ladder DACs in free air. Another disadvantage are temperature changes. Those can be avoided in our housing which keeps the temperature constant for each resistor of the ladder. Look at the above table. It shows you the accuracy needed for 24 bits of resolution which can only be achieved with laser trimming. The very best resistors today have an accuracy of ~0.01%. That means about 14 bits. What can also be seen is that due to so-called 'Johnson noise', you never exceed 24-bit accuracy in the analog domain. Johnson noise is the thermal self noise of a resistor itself. This can only be lowered by suppressing the ambient temperature. For a normal environment at 25°C (even higher inside many electronics), 32-bit resolution is commercial hooey. It's impossible. Johnson noise will dominate. Perhaps in the Arctic's sub-zero temps of -40°C, resistors will perform better but to be more precise, higher resolution is currently only possible in the digital domain. That's in fact our FPGA which runs at 400MHz using 64-bit words."


"Another  advantage for our DAC Two module is that it contains paired converters. Using the same number of modules as before, we now double the effective number of ladders. The current Pavane runs four modules per side, hence four ladders. The Adagio gets eight per channel even though you only see four. This doubling has a positive effect on noise, distortion and linearity. That's why we started an update program to get the Pavane to the same performance level. The current Pavane is now marked Level 1. Two more levels can be chosen, from Level 2 [+€826 ex VAT for the 192kHz broadcast module] to Level 3 [+€1'240 ex VAT for the 384kHz high-end version]. A final advantage of the DAC TWO module is that it frees up the slot for the external FPGA on the digital input board for future options. Back to the Adagio. Because we use a variable reference voltage, we had to redesign the boards. Because the modules need some voltage to work, it is not possible to go to zero. A safe minimum level is -60dB—quite low already—but to achieve true zero, we added a mute function. For matching the Adagio to every kind of amplifier, there is a new switch for each channel on the back. This lowers the output by -10dB; about 700mV RMS. Last but not least, we created some 3-pin trigger connectors on the back to switch power amps on and off; and use three 30VA not 15VA power transformers. 

"Sonically, the Adagio (or Pavane Level 2 or 3) goes a step further and is even more refined than what you've heard from us yet. It's also compliant now with 384kHz sample rates. Running the Adagio as a normal converter is realized by setting its volume to 12:15. This is equivalent to an upgraded Pavane run with a standard preamplifier. However, when the Adagio connects directly to a power amp, it relies on a new mind set. Now any kind of 'secret sauce' or 'signature' disappears. It certainly brings you closer to minute musical details but can also be a reason to change out cables or other types of tweaks. I don't have to tell you that the sum of all parts in the chain will have a clear effect on the final result. As to max output, setting that was a careful match between noise figures and voltage so we set it at just above 4/2Vrms for XLR/RCA. You probably have to increase the encoder's setting a bit more for very low-level recordings but in all cases we tried, including your Pass amps, adjustments were very convenient. With a 2Vrms output, the noise floor in amp-direct mode is now -155dB! That's because our converters run on twice the voltage and thrice the reference voltage as before. This boosted the Pavane's already very good noise figures by another 10dB. Finally, when connecting the Adagio to the mains for the very first time, use the remote to release the mute function. Only when the Adagio disconnects from the mains and then reconnects must this be done again. It takes about three weeks of use before the sound fully matures so leave it on for the duration."

Further specs are 100/640Ω output impedance on RCA/XLR in 0dB mode; and 100/320Ω in -10dB mode. THD is 0.006%. Digital connectivity is via BNC, coax, AES/EBU, USB and Toslink. Dimensions are 44 x 32 x 8.5cm, weight is 9kg. Again, the Adagio is not a Pavane plus volume control even though an original Pavane can be upgraded to become an Adagio minus volume control. And, its volume control is neither conventional analog nor lossy digital. The only other deck I'm aware of which also uses multiple R2R ladders to process different segments of its 24-bit binary code discretely before summing them and adjusts its reference voltage for purist volume control is the German/Russian Wagner Audio DreamDAC. That however starts at €14'000.