Digital Processor Reviews

I first spied the Ayre Codex two Januarys ago, at the 2015 Consumer Electronics Show, and its scrappy proletarian vibe sure made it look different from any other Ayre creation. On learning that its price would be well under $2000, I was immediately curious what Charley Hansen and his gang—makers of the $3450 QB-9^DSD USB digital-to-analog converter, plus a few five-figure amps and preamps—could create when cost is an object.

For the past decade or so, I haven't been using a preamplifier. The D/A processors I have been using all have volume controls, so I have been feeding their outputs directly to the power amplifiers. It would seem logical that having nothing in the signal path would have less of a degrading effect than a preamp's input and output sockets, switches, volume control, printed circuit-board traces, and active and passive parts, not to mention an additional pair of interconnects. However, with some of the preamplifiers I have auditioned in my system, there was no doubt that the sound quality improved compared with the direct connection from the digital processor.

The most recent of these preamps was the MBL N11 that Jason Victor Serinus reviewed in July 2021, which was preceded by the Pass Labs XP-32 I reviewed in March 2021, the Benchmark LA4 Kalman Rubinson reviewed in January 2020, and going back even further, the Ayre Acoustics KX-R Twenty I reviewed in December 2014, which was one of the products Ayre released to celebrate its 20th year of operation.

I am now reviewing the KX-8 line preamplifier, which costs $6500 in basic form.

Since its founding in 1993, Colorado-based Ayre Acoustics has made its name with amplifiers and preamplifiers based on truly balanced, solid-state circuitry that didn't use the ubiquitous panacea of loop negative feedback to produce linear behavior. Their first digital product was the D-1x DVD player, reviewed for Stereophile by Paul Bolin in February 2003, which offered unusually good video performance. The D-1x was followed by the C-5xe and DX-5 universal players, respectively reviewed by Wes Phillips (July 2005) and Michael Fremer (December 2010). But the most intriguing digital product to come from Ayre was the QB-9 digital processor. Reviewed by WP in October 2009, the QB-9 has just one input, USB, and uses Gordon Rankin's proprietary Streamlength code to give asynchronous operation, which in theory offers the best jitter suppression. "The QB-9 isn't a computer peripheral," said Ayre's marketing manager at that time, Steve Silberman. "It makes computers real high-end music sources"—a statement with which WP agreed.

Throughout the summer and fall of 2016, I worked on a project with Stereophile contributor Sasha Matson, recording, editing, mixing, and mastering—for release on 180gm LP, CD, and high-resolution download—an album of works that Sasha had composed for various chamber ensembles: Tight Lines. As you can read in the article we published about this project, for the vinyl release we decided not to master the discs directly from the hi-rez files, but to create an intermediate analog tape master. Feeling that audiophiles would want an LP that at some stage was "analog," we therefore needed to choose a D/A processor to drive the Studer open-reel tape recorder we were going to use.

John Stronczer, Bel Canto Design's technical spark plug, meets my definition of an electronics renaissance man, ranging as he does from designing single-ended amps that glow in the dark (the Orfeo) to digital processors (the Aida). Actually, digital circuitry is one of John's specialties, dating back to his days at Honeywell.

Stereophile normally doesn't review audio systems. We review individual components. We've made an exception for the Bel Canto Black system because it deserves to be evaluated as such. It consists of three dense, almost identically sized cases of black-anodized aluminum. One, the ASC1 Asynchronous Stream Controller, is what in a conventional system would be called a "preamplifier." The other two, a pair of MPS1 Mono PowerStreams, would in a conventional system be called "monoblock power amplifiers."

It's hard to know what the best strategy is for digital upgrades. Maybe you bought your first CD player when you became convinced that the format was going to succeed, and it seemed that players were about as good as they were going to get. Some time later, you tried one of the new outboard digital processors, and the sonic improvement was such that you just had to have it. Then you replaced the player itself with a CD transport, so you could benefit from improvements in servo control and digital output circuitry. At this point you were generally happy with your digital front-end—until you read about how 16-bit DACs (which is what your processor had) were old hat now that 20-bit DACs were available. But alas, your processor couldn't be upgraded, and was worth maybe 30% of what you'd paid for it. So you took a loss and bought a new-generation digital processor, and things were fine and dandy...for a while.