Review: FiiO E10, HRT HeadStreamer, and NuForce uDAC-2SE USB DAC/Headphone Amplifiers Page 2
HRT's latest offering is, somewhat unusually for the company, a combo device, shoehorning both a DAC and a headphone amplifier into a tiny package intended as a desktop or laptop companion. The little box (in form, it follows HRT's signature flattened tube configuration, though somewhat truncated in this case) is devoid of controls; you'll find a mini-USB input (clearly labeled "asynchronous"), a 1/8-inch minijack headphone output, and two ladders of orange LEDs that indicate signal lock at various sample rates, as well as the device's mute status. That's it - it's about as simple a device for the task as you can imagine, very much in keeping with HRT's design philosophy.
You read that right: no controls. No rocker switches, no volume buttons, no knob. I was a bit taken aback at first to find that one had to use a computer's software volume controls to adjust the HeadStreamer's output. Why'd they leave out a volume pot? Wouldn't I be losing precious bits via digital attenuation?
But not to worry - HRT's engineers have taken advantage of some not-often-implemented features of the USB audio device and human interface device classes. Each time the device pairs with the host computer, HRT engineer Kevin Halverson explained, the system's onboard volume controller is disabled; instead, the OS's software controls are redirected to remotely control an analog output attenuator in the HeadStreamer's output stage. The magic happens according to the rules of the USB audio device class; no custom driver is required for either OSX or Windows. It's very slick and seamless; simply select the HeadStreamer as your output device and you're good to go.
The downside, of course, is that you still have to use the up and down volume keys on your multimedia keyboard (or the onscreen menu on your computer/) to control the output volume of your headphone amp. Personally, I like having a knob to twist, but maybe I'm just finicky. In practice, I had no problems managing levels, though I found myself wishing for a volume pot for quick adjustments between tracks while listening to playlists including material with wildly different volume levels (I should probably just avoid randomly shuffling between the California Ear Unit's recording of Morton Feldman's "Rothko Chapel" and Gorguts' Obscura, I know, but that's the way I roll). But if you're OK with onscreen controls (and I suspect most people will be), you're in luck...in operation, on the UI front, it's as if you haven't changed anything at all. But sonically, it's a different story. The little box sounds quite good, very much in keeping with the impressive bang for the buck delivered by HRT's other products, and also in keeping with the high state of the art in small USB audio devices these days.
Beyond giving you access to your high-rez files at native resolution, the little box delivers a better overall headphone experience. Our HiFiMan HE-500 and Sennheiser HD-650 headphones - neither of which could be driven comfortably by our Mac's onboard audio output - were driven authoritatively by the HRT (while I wouldn't call the device a perfect match for a 300 Ohm headphone, it will certainly do a far better job than your computer's built-in headphone amp), and it played nicely with the low-impedance models we tried (including the Denon AH-D7000, to several sets of in-ears by Shure, Westone, and Altec-Lansing, to the V-Moda M-80) without undue hiss or noticable distortion. Bass was tight and focused and overall clarity was impressive with both sets of phones, comparing favorably sonically to our larger desktop amps (in this case, the Musical Fidelity V-Can and the CEntrance DACMini), though certainly not capable of the ear-splitting levels attainable with the bigger boxes. Not that you really need that sort of power in most cases, of course.