Digital Processor Reviews

Right now, I swear, Schiit Audio's Mike Moffat and Jason Stoddard are sitting there in California, smugly smirking at me and John Atkinson. While JA was struggling to properly measure Schiit's Ragnarok (Fate of the Gods) integrated amplifier for my review in the May 2016 issue, I sent Moffat an e-mail: "Are you smiling?"

"Yup," he replied. He'd known in advance that the Ragnarok wouldn't look good on standard tests. But he hadn't warned us: The Ragnarok's output-stage bias program responds to music sources, not signal generators.

It has been 20 years since I first became aware of the British company Data Conversion Systems, which manufactures audio products under the dCS brand. Rather than use off-the-shelf conversion chips, the groundbreaking dCS Elgar D/A converter, which I reviewed in our July 1997 issue, featured a then-unique D/A design that they called a Ring DAC. This featured a five-bit, unitary-weighted, discrete DAC running at 64 times the incoming data's sample rate—2.822MHz for 44.1kHz-based data, 3.07MHz for 48kHz-sampled data and its multiples—with upsampling and digital filtering and processing implemented in Field Programmable Gate Arrays (FPGAs). Oversampling to a very high sample rate allows the word length to be reduced without losing resolution, and use of a low-bit multi-bit DAC makes for very high accuracy in the analog voltage levels that describe the signal. (If this seems like voodoo, for a given signal bandwidth, bit depth and sample rate are related. To oversimplify, double the rate, and you can reduce the bit depth by one bit while preserving the overall resolution.)

"They're so damn hard to tell apart!"

So exclaimed my longtime pal and fellow audiophile Bruce Rowley when I revealed to him that T+A Elektroakustik's new DAC 8 DSD digital-to-analog converter ($3995) had arrived for review, just after I'd finished writing up the Ayre Acoustics Codex DAC–headphone amp ($1795). Bruce had recently compared his own brand-new Codex with a DAC he'd owned for a couple years, both costing about the same but built to very different designs. He was surprised that, after carefully matching levels and working to eliminate any other variables, they sounded more alike than not, and only slightly different even after hours of listening. Technically, these were two very different animals.

Approximately 33¹/₃ years after AudioQuest's first phono cartridge, the company announced two new USB D/A headphone amplifiers: the DragonFly Black ($99) and the DragonFly Red ($199). Both have circuits designed by the engineer responsible for the original DragonFly—Gordon Rankin, of Wavelength Audio—and both have the novel distinction of requiring considerably less operating power than their predecessors, so much less that the new DragonFlys can be used with iPhones, iPads, and various other mobile devices.

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.

Researchers at MIT recently discovered a "music channel" in the human brain. These neural pathways respond to all kinds of music—and only to music. "A listener may relish the sampled genre or revile it," Natalie Angier wrote in the New York Times. "No matter. When a musical passage is played, a distinct set of neurons tucked inside a furrow of a listener's auditory cortex will fire in response"

The night before I started to write this review, PBS began a five-part series on computers called "The Machine that Changed the World." The first episode described the development of the ENIAC (Electronic Numerical Integrator and Accumulator), the first electronic computer. The ENIAC used 18,000 vacuum tubes, had over 500,000 solder joints, required a room 30' by 50', had to be physically reprogrammed with patch cords to perform different tasks, and packed less computing power than today's $4.99 pocket calculator.