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 2.04, Qobuz Hifi, Tidal Hifi, COS Engineering D1, Metrum Hex, AURALiC Vega, Aqua Hifi La Scala MkII, SOtM dX-USB HD w. super-clock upgrade & mBPS-d2s, Apple iPod Classic 160GB (AIFF), Astell& Kern AK100 modified by Red Wine Audio, Cambridge Audio iD100, Pro-Ject Dock Box S Digital, Pure i20, S.A. Lab Lilt [on loan], Vinnie Rossi LIO [on loan]
Preamplifier: COS Engineering D1, Nagra Jazz, Esoteric C-03, Bent Audio Tap-X, Vinnie Rossi LIO [on loan]
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; AURALiC Merak [on loan], Vinnie Rossi LIO [on loan]
Loudspeakers: Albedo Audio Aptica; EnigmAcoustics Mythology 1; soundkaos Wave 40; Boenicke Audio W5se; Zu Audio Submission; German Physiks HRS-120, Gallo Strada II w. TR-3D subwoofer, Apertura Audio Adamante [on review], sounddeco Sigma 2 [on review], Coin Audio Mansion Compact [on review]
Cables: Complete loom of Zu Event MkI and MkII; KingRex uArt double-header USB; Tombo Trøn S/PDIF; van den Hul AES/EBU; AudioQuest Diamond glass-fibre Toslink; Arkana Research XLR/RCA and speaker cables [on loan]
Power delivery: Vibex Granada/Alhambra on all components, 5m cords to amp/s and subwoofer
Equipment rack: Artesania Audio Exoteryc double-wide 3-tier with optional glass shelves and Krion or glass-based Exoteryc stand/s for amp/s
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: from $4'997 for A Capella 2, $8'297 for Virtuoso
"My name is Kevin Welsh. I connected today with your bio on 6moons. I’m someone who has taken the less traveled path, sometimes intentionally, sometimes not. Often with a few lessons learned and always better for the experience. I stumbled into making high-end audio components a few years ago. I sold a software copyright and had some play money with which to upgrade my 2-channel system. I wanted a DAC and found great reviews of the Weiss202. I made it mine. It was an amazingly clear component and so emotionally engaging as well. Then I was off to search for the best device to feed it, having been using my Dell laptop. I read lots of 'stuff' about linear power supplies in digital and I thought it was a hoax. But some small part of me was curious and some larger part of me wanted to prove everyone wrong. So I set out to do just that.

"I made a purpose-built PC and tried power supplies from high-end audio manufacturers, industrial manufacturers, medical. To my surprise, many sounded different. Then I found one from a Ham Radio company whose power supply was a game changer. I started selling Windows-based media players under the name Musica Pristina. I was obsessed with creating the most accurate sounding player I could build. At the same time, I was making phone calls to engineering firms to figure this all out. Surely they knew what mattered. Most told me the tired line that 0’s are 0’s and 1’s are 1’s. One guy, however, put me in touch with someone he knew from IBM who did "something with audio". That someone was Dave Davenport, and he happened to live 2 miles from me.

"Dave had a few loosely held theories as to what mattered. More importantly, he urged me to trust my ears.Dave also had a great DIY DAC line (transformer coupled, fully balanced dual mono signal path, tube output stage). One day we put his Mark III revision of the DAC up against my Weiss. He lost and he took it like a man. He also took it like an inventor and came back a few months later with his Mark IV. I immediately sold my Weiss and Dave and I began a loosely connected partnership selling players and DACs. (Oh, it sounded amazing.) In 2014, having hit the wall where I could no longer improve the accuracy of my playback, I decided to abandon Windows and try a few other options. The current version of our player is the result of this effort and we’re very proud of what we’ve achieved. Hence I'd like to explore getting it reviewed." - Kevin Welsh

I had a few questions, particularly about avoiding that dreaded gomboo called WiFi. Apparently I'm the only reviewer who hates it. But hey, viva la difference as they said during the French revolution. "The UI is a set of web pages that live on the device. So you can control it with any other device on your network. In your case, your iMac would act as the remote control by pulling up the UI in Safari. The first step is to tell the A Cappella II where your music is. It will work with USB drives but I prefer Ethernet NAS by far. Is it safe to assume you have music available in a shared folder? If so, you tell the A Cappella II where that music is, give it a few seconds (maybe minutes if you have a massive library) to index the library (nothing happens to your files, the connection is read-only) and you're good. You can also copy music to the SSD over your network by pasting files into a shared folder that lives on the A Cappella. I'm a software developer by trade and wrote the interface to be easy to use for the digital audio novice. A lot of customers of our Windows-based systems found JRiver too complex and prefer our thinned-out version of Foobar2000." This proposed assignment was moving in a happy direction. No headache-inducing WiFi nausea. Good riddance!

I asked Kevin to show me a few screen shots of his app to prejudge how it might compare to iTunes. That's my default library navigation skin behind which PureMusic or Audirvana do their signal routing bit. Then I explained that my iMac lives at the end of a 20m CAT6A cable; that we don't have a second one running back to the router, hence couldn't plug his server into the same router at the same time; that we are in fact not a networked but discrete household—my wife's computer is on a different ISDN router and phone line entirely—and thus also don't tap into any shared music folder. Couldn't I use a short CAT6a link between iMac and A Capella II? I had in the past transferred files between old and new iMacs that way. "You can’t merely use a CAT link between two devices without also handing out an IP address. Or, we'd need to set up static IP addresses which would increase complexity exponentially. So the simplest option could be this: I send you a gigabit switch. That's essentially an Ethernet splitter box. You connect it to your 20m Ethernet cable. You connect it to your iMac. You connect it to my machine. You connect the A Cappella to your DAC via USB. You copy files to the A Cappella's internal storage from your iMac. You control the A Cappella with the browser on your iMac. At that point, the gigabit switch, the iMac and the extra patch cords are not in the signal path at all. The A Cappella would be playing from internal storage. Does that sound reasonable to you?" Sure did. "Yes, boss!" Given how this would be a short-term review loaner, I told him not to bother with leathering his ride up with the 2TB SSD option. The standard 1TB would suffice. After all, just how many files did I have to transfer to get a good fix on his deck's performance vis-à-vis streaming the same files from my customary iMac?