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Positive Feedback ISSUE 70
november/december 2013


The Audio Circular: No.7 in a Series of Parallel Narratives - The Wyred4Sound uDAC-HD
by Gary Beard


Wyred4Sound uDAC-HD

It is quite amazing how many (relatively) inexpensive, small-footprint digital to analog converters there are on the market right now. I am fortunate to have had a few weeks with a sterling unit from well known high-fidelity audio equipment manufacturer Wyred4Sound. W4S's Clint Hartman sent me the uDAC-HD last summer, and I was only able to enjoy it for a short time, personal matters got in the way of the timely completion of this work, so my apologies to Wyred4Sound for taking so long to complete this audio narrative. Onward...

 Little Box = Big Sound!

Other than the Halide Designs DACHD, the W4S uDAC-HD is the first of the current crop of mini-DACs I've heard in my own system. The diminutive uDAC-HD is only 3.5" square and 1" high; certainly small enough to be a desktop audiophile's dream. Per W4S, the HD uses an asynchronous XMOS design and is certified USB 2.0 High Speed and Audio Class 2.0 compliant. While it requires a simple ASIO driver install for PC machines, none is needed for Mac (10.6.4 and above) or Linux systems. The uDAC-HD's converter platform is based on the same ESS Sabre chipset that Wyred4Sound uses in its flagship DAC2. In lieu of a direct line out from the DAC chip, W4S drives the RCA line-level output of the HD using their "STP-SE" line-stage topology. While this is my first experience with a W4S product, based upon their experience in building digital components, it seemed a pretty good bet this would be a well implemented design. And it certainly seems they have hit the mark. The uDAC-HD just does its job, simply and well, without glitches of any kind. That, my audio-friends, is a pretty good start for any computer-based audio product.

Wyred4Sound uDAC-HD

Simple and Well... Sounds Good Too!

During my short time with the HD, I listened to all manner of music, mostly 16-bit 44.1 kHz PCM, but also high resolution tracks in both 24/96kHz and 24/192kHz. The uDAC-HD never wavered, playing each track with a self-assured sound that was both predictable and smashing good fun.

While the uDAC-HD did sound a bit mechanical in the first few days--never really harsh, just not quite realistic—after a while it smoothed out and became a bit more organic. It didn't take long to notice a sonic similarity between the uDAC-HD and my reference Mytek DSD 192 Stereo DAC. I can only assume this is due to the ESS chipset. But whereas the Mytek is a bit on the languid, yet powerful dark side of neutral, the HD is as bright and cheery as a sunny day for an overachiever. In addition to breathing life into every recording with this lit-up presentation, the uDAC-HD is highly resolving of fine detail and has a punchy, toe-tapping sound that gives this munchkin of a digital converter some serious rhythmic drive. It has a wide stage and great localization of instruments, and the images seem to project toward the listening seat, thereby getting me closer to the performance.

I found the uDAC-HD to have very good macro dynamic capability as well as amazing bass reproduction through a review pair of the fab Von Schweikert VR-22 loudspeakers. As I listened to "Capri Calling" from Yello's Baby album, I noted the sound to be "...hauntingly good." Bass was tight, deep, and extremely dynamic.

The HD is more forward and insistent and crisp than the Mytek, which is more refined, has better depth, and a generally more dimensional presentation. In reality, the sonic difference between the two is more of a Yin/Yang thing, analogous to the tube amps vs. solid-state amp argument if you will. And while the HD's staging is flatter, and timbre is not quite as authentic as the Mytek, I do find the uDAC-HD's sound captivating in its own way. The HD has an arguably "better" (at least more obvious) top end that gives the aural landscape more light with its treble energy. I don't mean it is hot, but again, I never fell asleep while listening. Air guitar, you bet, but snoozing, no way!

While it clearly sounds different than my reference, W4S's mini-nod to hi-rez replication is great fun, and even a little addictive. The one constant I heard in the uDAC-HD was its propulsive quality. Yessiree folks, it's that dang ol' audiophool PRAT (pace/rhythm/timing) thing again! I believe in it, I hear it; and I think the uDAC-HD has it in spades... And that is a good thing. While the Mytek seduces me like a fine Cabernet, the uDAC-HD knocked me in the head with the beat and BAM! I was shower-singing the incorrect lyrics and loving every off-key minute.

Headin' Out?

In addition to its duties as main system digital to analog converter, the uDAC-HD is also a wonderful headphone amp, and would be an excellent portable choice for audiophiles on the go. It features a discrete Class A headphone amplifier, but due to this circuit's high electrical demand, it can only be used when the 9 volt DC power supply is connected. I used the 1/4" headphone output with my Beyer Dynamic DT 770 Pro headphones, and I can attest that with the wall wart power supply connected, music sounded terrific and mirrored the sonic qualities I heard through the main system speakers. When switching to USB bus power from my laptop (as one would in a portable situation where no 120 volt source is available or desired), there was an obvious softening of the sound; it was still very good, but I plainly noticed the difference as soon as I switched back to the separate power supply. While audiophiles will want to plug the DAC into 120 volt power whenever possible, the unit still sounds good when powered straight from a computer USB port.

Regarding the wall wart PSU, I have accolades and one quibble. I do like the fact that the wall wart case looks different than all the others I have—I would always recognize it as the proper one for the uDAC-HD--and I also appreciate that there is a power LED indicator. That said: the power cord could be longer. It is so short that I couldn't place the DAC in my preferred location, which buried the HDs way cool W4S logo signal lock light deep in a sea of cables, behind all the other less cool looking gear. No harm, no foul perhaps, but I really wanted to see it. It looks awesome when the room lights are low!


All things considered, the uDAC-HD is somewhat of a triumph of the law of diminishing returns. The sound I heard out of this Klondike bar sized DAC is really good and it plays hi-rez audio files up to 24/192 without even a hint of protest. The uDAC-HD is an engagingly musical component and for the Spartan price of $499.00 retail, it could fit the bill in a variety of high-end audio applications; from main to streaming to headphone amp. Go have a listen.

Gary L. Beard


Retail: $499.00 USD