Digital Processor Reviews

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"

I eat bits for breakfast. Lunch is a simple bit-sized snack. And dinner is the analog to real food. This has been my routine these past four years as editor of AudioStream.com, where we digest all things computer audio.

In that time I've reviewed over 100 digital-to-analog converters, ranging in price from $60 to over $12,000. This adds up to roughly 150,000 words spilled on DACs. You'd think my pen would be running dry—especially if you feel, as some do, that all DACs sound pretty much the same. If that were the case, I could have written just one review, for that very first DAC, then cut and pasted it for all the rest. What was I thinking?

Apogee Electronics Corp. has been in business for 30 years, and I've always thought of them as one of the pro-audio companies responsible for moving digital in the right direction. They've made their mark in recording studios around the planet with digital-audio interfaces and master clocks that have long been considered some of the most technically and sonically advanced, and that were probably used in a high percentage of the recordings in your collection. So when I saw Apogee pop up at the consumer end of the market with a technically unique product, budget-priced at $295, it got my attention.