Digital Processor Reviews

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Jon Iverson Posted: Feb 16, 2017 4 comments
Now that we've entered a world of post-disc audio (sorry, AnalogPlanet.com), audiophile streaming and file-playback products have appeared by the hundreds, and many companies are on their second, third, or even fourth-generation models.

The Chinese company Auralic Limited has been pushing bits around for seven years, releasing a half-dozen streaming and network devices. Their newest, the Altair, combines in a single package the functions of a DAC, streamer, and headphone amplifier with volume control, allowing it also to operate as an all-digital-system preamplifier. Just add power amp and speakers.

Herb Reichert Posted: Jan 18, 2017 17 comments
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.

Larry Greenhill Posted: Nov 23, 2016 6 comments
In the February 2010 issue of Stereophile, I reviewed Bryston's first standalone digital-to-analog converter, the BDA-1 ($1995). Five years later, Bryston released the BDA-2, which replaced the BDA-1's 24-bit/192kHz Crystal CS-4398 DAC with a pair of AKM DAC chips in balanced mode. In a February 2016 Follow-Up (footnote 1) I reported that the BDA-2 deepened and widened the BDA-1's soundstage, among other performance gains.
John Atkinson Posted: Nov 18, 2016 3 comments
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.)
Jim Austin Posted: Oct 28, 2016 0 comments
When I moved to New York City about a year ago, I was prepared to dislike Brooklyn. Judging it by its reputation as the apotheosis of cool, I envisioned the borough full of good-looking people engaged in pointless acts of mindless, stylish conformity, from man-buns to single-origin pour-over coffee. (Anyone up for adult kickball?) As I've written before, about Portland, Maine—a hipster place much indebted to Brooklyn—I greatly prefer deeply committed idiosyncrasy to mindless conformity.
Jon Iverson Posted: Oct 04, 2016 13 comments
"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.

Herb Reichert Posted: Aug 30, 2016 5 comments
I am a lucky person. Who gets to be an artist, an aspiring griot, and a Stereophile reporter? Who gets to stay at home in paint-smeared pajamas, draw pictures of teapots and barn owls . . . and then, on top of everything, gets paid to listen to music made by Henryk Szeryng, Eugene Hütz, and Winston Reedy? C'est moi!

I have groovy friends, too: other eccentric artists, scruffy musicians, recording and mastering engineers, beekeepers, authors and editors, art and junk collectors, tube wizards, turntable savants, DJs, Mensa-type amp designers, bat-shit-crazy poet-philosophers, and unrepentant hoarders.

Art Dudley Posted: Aug 25, 2016 5 comments
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.
Michael Fremer Posted: Jul 21, 2016 10 comments
Simaudio saw disc-based digital audio in its rear-view mirror at least as far back as 2011, when it introduced the Moon Evolution 650D and 750D—two iterations of what it called a "digital-to-analog converter CD transport." These were actually multiple-input CD players, but Simaudio was evidently so eager to distance itself from the spinning disc that it went with a product category that, in spite of its cumbersome, run-on name, drew a clean line between the disc-reading and signal-processing functions—while bestowing upon the former second-class citizenship.
Jon Iverson Posted: May 25, 2016 4 comments
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-9DSD USB digital-to-analog converter, plus a few five-figure amps and preamps—could create when cost is an object.
Jim Austin Posted: May 19, 2016 3 comments
I was lying on a mattress on the floor of an empty apartment on Manhattan's Upper West Side. Not as grim as it sounds—it's a nice apartment, and the mattress was new, and had just been delivered—but it was hot (no air-conditioning), and my family and my furniture were still in my condo up in Maine, and I was lonely. I needed some cheering up. Which is how I rationalized the decision to buy an Explorer2, Meridian Audio's tiny, inexpensive ($299) digital-to-analog converter.
Jim Austin Posted: Apr 28, 2016 0 comments
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"
Robert Harley Posted: Apr 13, 2016 Published: Dec 01, 1995 0 comments
Of all the products I've reviewed or auditioned, a select few jump out as "best buy" recommendations. Almost universally, such products are liked by a wide range of audiophiles, and seem to match well sonically to many systems. Moreover, these products all have outstanding value; they offer a higher level of musical performance than you'd expect from the price.
Robert Harley Posted: Apr 05, 2016 Published: Jun 01, 1992 2 comments
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.
John Atkinson Posted: Jan 27, 2016 29 comments
Like all men, I learned at an early age to resist the allure of a pretty face.

Okay—I learned that I should try to resist the allure of a pretty face.

Okay, I confess: I have never been able to resist the allure of a pretty face. Which is why, when I first clapped eyes on the Mojo D/A headphone amplifier from English company Chord Electronics, at an event hosted by Manhattan retailer Stereo Exchange, I had to borrow a sample for review.

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