Halide Design • DAC HD Digital-to-Analog Converter

An asynchronous high-resolution USB DAC with "surprising" sound and a budget price.

by Marc Mickelson | June 30, 2012

wasn't exactly Nostradamus, but I did contemplate computer audio over twenty years ago, after I bought my first PC. I'm sure I wasn't alone. After all, CDs are storage media similar to a hard drive, and the music on them is data. Therefore, I proudly reasoned, why not store music on my hot new computer? Of course, my bubble burst when I did the math and discovered that a 40-minute CD would require a hard drive with greater than ten times the capacity of my 30MB drive. Such a beast wouldn't exist for a couple of years, with another decade after that until hard-drive capacity would be sufficient for music storage and the PC's Windows operating system.

Nowadays, with hard drives measured in terabytes and costing a pittance, computer audio is not only viable but here to stay. Yet I am still contemplating. Oh, I've done my due diligence on the subject and even turned my laptop into a makeshift music server, but I'm still a physical-media guy, my laptop, which I spend too much time in front of, coming in a distant third among sources.

Halide Design seems to understand guys like me. The company's S/PDIF Bridge ($395), which I wrote about almost two years ago, was aimed squarely at entrenched audiophiles who owned traditional digital-to-analog converters without USB inputs. The Bridge does just what its name implies -- converts a computer's USB output to S/PDIF digital (either coaxial or BNC), packing a great deal of high-tech circuitry into a very small space: the CNC-milled aluminum barrel of its RCA or BNC connector. This goes double for Halide Design's next product, the DAC HD. Like the Bridge, it implements Gordon Rankin's Streamlength asynchronous protocol for sending digital data from a computer with the least amount of jitter. When the DAC is slaved to the computer, timing errors -- jitter -- are introduced, affecting sound quality in harmful ways. Streamlength solves this problem by turning the digital-playback chain around. The low-jitter master clock located in the DAC HD controls the audio transfer rate from the computer, and jitter is reduced significantly. The DAC HD accomplishes this with the standard Windows, Macintosh or even Linux USB drivers, preserving the ease of plug-and-play installation.

However, the DAC HD goes a step further than USB-to-S/PDIF conversion, taking care of the digital-to-analog conversion as well. Its Texas Instruments input receiver includes a microprocessor that runs the Streamlength software, and its DAC chip, the Wolfson WM8716, handles incoming data up to 24 bits and 96kHz. All of this is housed within a milled aluminum case that's about half the size of a deck of cards. While it's easy to think of the DAC HD as a feat of miniaturization, its guiding principle is hi-fi sound, right down to the cabling used: a Wireworld Starlight USB cable on its digital input and silver wire terminated in Eichmann silver RCAs at its analog output. And the whole thing is cryogenically treated for "a smoother, more resolved sound."

Before getting the DAC HD, which I've been listening to off and on for months, I quizzed the company principals about audiophilia's version of the boxers-versus-briefs debate: PC or Mac? I had planned to get a Mac solely for use as a computer-audio source, a purchase I haven't gotten around to making -- yet. The preponderance of opinion is that the Mac is superior to the Windows PC, although the people at Halide Design admit to being "source agnostics." In regard to the DAC HD, they offered that "It should sound pretty similar PC or MacBook . . . ;that's part of the design. It's asynch, and the power supply is designed to filter out everything as much as possible." In their view, the playback software is much more important than the hardware: ". . .the default playback software in Windows totally screws up the sound. On Mac, there's a plug-in for iTunes called BitPerfect that fixes the problem (and will automatically set the correct sampling rate). [It's] super cheap and easy."

As with the S/PDIF Bridge, setup of the DAC HD was stupid easy -- for PC at least. In fact, there's really nothing to do other than connect it to the computer and then choose it as the default sound device. Directions come in the box, but if you have a minimum of computer savvy, you can ignore them and still be playing music in minutes. An important choice you will need to make before purchase is the length of the DAC HD's USB cable. Two meters is standard, with up to seven meters available.

ecause I rip many familiar and telling cuts for CD-R samplers that I take to most shows, my PC has a fair amount of demo music loaded on it. To this I added even more, including high-res cuts from Reference Recordings. Thus, while my computer's primary use isn't as a music server, it does have its toes dangling in the waters. As for playback software, I installed foobar 2000 v1.1.1 when I wrote about the S/PDIF Bridge, and I continue to use that.

The price of the DAC HD places it firmly in the budget category, which normally raises questions of a product's performance vis-à-vis that of its more expensive competition. My system is not exactly a welcoming environment for new source components, outfitted as it is with revealing electronics and speakers along with high-level digital and analog playback. The sound of new products has nowhere to hide, and stiff competition lurks at the next input.

Even though my laptop is for work first and listening second, an indication of the fact that I have done almost nothing to enhance its sound quality, it was impossible to deem it as anything but a true hi-fi source when used with the DAC HD. I was delighted right from the start with the ease and purity of the sound -- surprised even, given my memories of budget-priced DACs from days of yore. There was nothing immediately compromised about the "budget" DAC HD's sound, not even its bass, which my listening notes described as "deep, agile, not lacking in heft." Given that the DAC HD has no power supply of its own, getting its power from the computer, I would not have predicted this, but then I also would not have predicted an overall character that greatly belied the DAC HD's price. With Windows laptops costing under $500, the DAC HD can be part of a sub-$1000 playback system that, I am confident, will challenge CD players costing double and triple this amount. Again, surprising.

Among the first cuts I played were ones from my CES 2012 CD-R sampler. I ripped and burned these with Exact Audio Copy. I choose cuts for my samplers based on their ability to reveal telling details about the demo systems I hear, not because they are sonic spectaculars (although some of them certainly are). As I look at the cuts I compiled early this year, I realize that I must have been on a quest for superior inner detail, as so much of what was on that CD-R was aimed squarely at revealing this. Among these, the cuts from The Hot Guitars of Biller and Wakefield [HMG 3006], a country-swing collection of mostly instrumentals played on slide guitar and Fender Telecaster with sparse accompaniment, were especially good at divulging spatial cues and tonal quality. The recording's flinty dryness left systems that leaned that way nowhere to hide. The DAC HD not only captured this essential nature of the recording, it didn't exacerbate it, finding the right balance between that dryness and its own inherent smoothness. This is what those cuts revealed -- that the DAC HD is smooth, and not ruthless in the way it conveys detail even into the midrange-treble transition region. Again thinking back to DACs from digital's earlier days, when the upper midrange/lower treble was the Achilles heel, the DAC HD's performance here was not only welcome but unanticipated, especially given its price.

Delicacy and power were also in abundance, as cuts from Roseanne Cash and Suzanne Vega demonstrated. Cash's Ten Song Demo [Capitol 112364] has very appealing, deeply felt music captured with great instrumental delineation and tonal naturalness, while Vega's Nine Objects of Desire [A&M 540583], which I've mentioned in many, many reviews, is more about soundstaging -- which seems artificial yet interesting -- and bandwidth, especially down into the bass. Again, the DAC HD conveyed the unique signatures of the recordings; it also didn't parse the music into mere collections of details, retaining the emotion and meaning. And there's incredible instrumental diversity at work in these two recordings, not to mention the differences in Cash's and Vega's voices. What Roy Gregory asserts is really true: better equipment makes for more intelligible intentions and thus more meaningful performances -- all of which this $500 DAC revealed.

The HD part of this DAC was even more telling than its CD-resolution performance. A while back Reference Recordings sent me a high-resolution sampler of cuts in .WAV format, and I've had them on my laptop since. I have the CDs from which a few of them come, making comparisons between CD resolution and high resolution, specifically the 24-bit/96kHz speed limit for the DAC HD, easy. The difference in dynamic range was immediately apparent, with the high-res cuts revealing low-level detail to the noise floor and slightly greater power at full-tilt volume levels. But it was really everything that happened in between that made the DAC HD's way with high-resolution files distinctly better. The differences between 16/44.1 and 24/96 (or 24/48, to a lesser extent) were signaled by more delicacy and space within the soundstage, more air and low-end grunt, more midrange purity, more more. Cuts from Mike Garson's Jazz Hat [Reference Recordings RR-114] and Hot Club of San Francisco's Yerba Buena Bounce [Reference Recordings RR-109] were revealing, but some of the big orchestral numbers, which Reference Recordings has proved over time to be proficient at capturing, were particularly telling. Delineation of the orchestra's sections and, again, its sheer dynamic range were awesome in the literal sense of the word.

Lest you think otherwise, however, there is room for improvement -- or perhaps just different. The DAC HD doesn't have the incisiveness of the Esoteric K-01 or Ayre DX-5, both of which can also function as USB DACs. It sounds more polite, even mellow. Its smoothness does reduce textural variation some, also compared to what the much more expensive units accomplish. However, I heard something similar when I used the DX-5 as a DAC: recording-to-recording variation that was apparent when the DX-5 played physical media was reduced when the bits came off the computer. Finally, the DAC HD's high-frequency energy seems ever so slightly subdued. This is consistent with the "slow roll-off" filter setting Halide Design chose for use with the Wolfson DAC. "We felt [this] combined the best features of the NOS (non-oversampled) tone with that of the more standard 'brick wall' type of filter." Given that this is digital, "slightly subdued" treble is not entirely a bad thing.

There are also a couple of things worth keeping in mind about the Toshiba laptop that sent bits to the DAC HD. First, it is again a working computer, not one optimized for music playback in any way. I'm sure that clearing the system of various applications that run in the background would improve performance, perhaps dramatically, as the system wouldn't be splitting its resources among competing processes. Second, foobar 2000, the freeware program I use for playback, can certainly be improved upon with a commercial PC-based program like J.River. Finally, Gordon Rankin of Wavelength Audio, among others, believes that the Macintosh is superior to the PC as an audio source, and not by a small margin. None of these things, I think, falls into the category of "your mileage may vary." Rather, they come down to "you can do even better" with some additional cost -- and possibly none at all.

o far my small, deliberate steps into the realm of computer audio have been painless and enlightening -- thanks to the products of Halide Design, which not only work without a hitch but do so with sonics that are clearly at the heart of their creation. The high regard I have for the S/PDIF Bridge is only elevated for the DAC HD, which adds refined-sounding digital-to-analog conversion to the feature set for a mere $100 extra. In fact, the DAC HD sounds so good that even if you have an existing non-USB DAC that you use with the S/PDIF Bridge, you really need to give it a listen, as it may simplify your computer-based playback rig and add high-resolution capabilities. It has nudged a stubborn late adopter like me a step closer to adding a computer to my audio system, and not for the sake of convenience. Connected to the DAC HD, the computer fits right in sonically.