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System N°12

Reviewer: Srajan Ebaen
Financial interests: click here
Sources: iMac 27" fully loaded, Audirvana 3, Soundaware D300Ref, Denafrips Terminator with 32 x upsampler
Pre/power: Vinnie Rossi L2 Signature w. Elrog ER50, LinnenberG Liszt
Loudspeakers: Audio Physic Codex, Børresen 02
Cables: Allnic Audio ZL3000/5000
Power delivery: Vibex Granada/Alhambra 
Equipment rack: Artesanía Audio Exoteryc & amp stands
Room: 5 x 10m continuing into open space
Review component retail: $15'000/pr AGD Vivace, $15'000 Merrill Element 114

Systematically. It's how we'd like to assemble a satisfying hifi. The actual route to it is often more haphazard. Even reviewers can chance upon an unexpectedly winning combination well after a review first published. So these short features grouped under the same constellation logo are about the grace of hindsight, occasionally from sheer dumb luck when certain items just so happened to be on hand and produced unexpected sparks. In all cases, our archives will already have published feature reviews on the main components. But those reviews are about parts. Today's report is about proven combinations. Often the key players will be the amp+speaker pairing. After the room, that's the biggest variable. Adding a particular digital source (I don't do vinyl) won't markedly tip the balance or wipe out the winning bits. Neither will cables past a base level of competence. So don't expect complete itineraries. This is about locking in a particular sonic flavor or presentation with the most important determinants. Sorting out the secondary and tertiary players remains at your own discretion.

AGD Vivace fronted by Vinnie Rossi L2 Signature direct-heated triode preamp with Elrog ER50 playing Audio Physic Codex 4-way speakers.

At school, getting an A was far better than a D. When it comes to operational mode, class A amps in hifi are still more prestigious (pretentious?) than class D. Rolling the D-ice from ICEpower to Pascal, Cherry/Marachino to TI, Hypex and nCore to Purifi with Aavik, Auralic, Bel Canto, Gato, Nord, S.P.E.C., Wyred4 and others, I've heard a bit over the years. Curiously, today I don't listen to it outside of reviews even though we actually own a few D-oers. In 2020, I came across two which equaled and/or eclipsed our powerful 1MHz class A/B LinnenberG Liszt monos with their lateral Exicon Mosfets. I had neither funds nor dire need to add one to our collection. Yet on sound, I easily could have. Why? I'd characterize both as high-power Bakoon types. Regular readers know. I rate the 25wpc Bakoon AMP-13R highest in our digs. What the D-enizens of far more power shared were fast-switching GaN aka gallium nitride transistors. One was the AGD Vivace mono, the other the Merrill Element 114 stereo amp. Expensive like established class A, neither was based on OEM modules to represent a proprietary solution instead.

Børresen 02 powered by Merrill Audio Element 114 fronted by COS Engineering D1 DAC/pre.

Both had amazing speed and transparency plus a fully developed sophisticated top end where prior class D had always come up short when referenced against wide-bandwidth direct-coupled class AB variants. Bass was superbly controlled and defined, not elephantine. Both claim to be unperturbed by low impedance, are utterly quiet and do lucid mode at a very high level. In short, these were true high-resolution champs, not warm comfort-sound types.

Alberto Guerra, designer of the Vivace, spent his prior career on the development of GaN parts. His review thus contains a lot of solid tech info. Unconventionally, Alberto packages his entire miniature GaN output stage inside a KT88 bulb. Typical tube pins mean it can be replaced to be modular. He's already announced higher-power KT150 GaNTubes which can be swapped in to change sonics; or create 75% more power in conjunction with a factory mod to raise Vivace's voltage rails. Merrill Wettasinghe hides his circuit from prying eyes with tamper-proof bolts, then gilds his lily with a very posh enclosure and display. Neither of these men pursue max power density for the lowest price like conventional class D does. Rather, they embrace new faster-switching parts for reduced dead times and performance beyond classic linear circuits.

A hi-tech message in a KT88 bottle.

Due to audible speed—emphatic lack of haze, blur, thickness, softness or padding—plus crystalline clarity, these amps may confound at first. They could overwhelm with raw detail density. They could demand a reboot of expectations and perspective like first meeting a properly adjusted Raal Requisite SR1a ribbon headphone. If post acclimation you still hanker for extra curves, strap on a subtly endowed preamp like a Nagra Classic or, for a bit more, a Linear Tube Audio MZ3 or, for still more, a direct-heated direct-coupled triode like an Allnic or Vinnie Rossi. None of the glowing decks will hit the brakes to any meaningful extent. But they will add a more lingering elastic aspect which you might just call a perfect wedding. For listeners who value speed über alles like still unlimited stretches of German Audiobahn, a direct-to-DAC connection could be their ultimate choice for a modern ultra-res system. Here matching speakers, cables and power delivery like Børresen/Ansuz would be obvious if costly candidates. But today's amps cost dearly, too Just so, class D has made real progress. And beyond superb sound, these GaN implementations still deliver high-current low-impedance drive into tougher loads and bass control that seems beyond nearly all non-switching amps I've heard. All in, those factors could become go-to amplifier solutions, period; or be particularly keen when you have dastardly loads or aren't sure what type of beastly speaker you might end up with one fine day.

Second opinion from Dawid Grzyb: "Class D being exclusively fit for driving subwoofers is a seriously outdated stereotype. A pair of NuForce Ref9 V3SE monos I owned years ago had already altered my take on it. Several class D machines I subsequently reviewed reassured me in that. To now have a change of heart on the subject, I'd really have to audition something crappy. Is that actually possible with modern class D OEM circuits? A S.P.E.C. RSA-M99 arrived October 2019. Not only did it look good, it didn't sound like 'typical' class D. Its performance was in the ballpark of what tube SET usually do. The concept of having this type sound with stout power plus none of the usual drawbacks of SET could easily flip a mental switch. At the least it signals the versatility of class D today.

"A set of Audiodinamica BeCube monos two months later didn't sound like the RSA-M99. On quality it wasn't even a contest. That was fine considering the rather significant price gap and stock Hypex module. Still, it sat at the opposite end of dry, pale, thin, sharp and chiseled. Taking the same pair for a spin, Audiodinamica's local representative subsequently called me very surprised by how rich and meaty they sounded. The Rethm Maarga I reviewed a while ago had active isobaric subs. Their maker Jacob George relied on internal class A/B amps before switching to 400W class D modules. When a widebander manufacturer makes such a move, it's telling. Next, Alberto Guerra's Vivace monos arrived several weeks ago [above]. I'll refrain from commenting much as my first AGD Production review goes live right after this article. What I will say is that Vivace's voicing isn't comparable to any class D I've heard. It belongs in the exact opposite corner of S.P.E.C. Qualities include sunny, energetic, open, quick, accurate and insightful but there's a lot more to Vivace. The point is, 'typical' class D sound has become a myth. Class D operation no longer predicts a particular sound. It all depends on implementation. And that spans an amazingly broad gamut."