Digital Processor Reviews

Consumer audio hasn't enjoyed many success stories in recent years, so this one stands out: According to distributor Elite Audio/Video, their USB-based Music Streamer D/A converters, designed and built in California by High Resolution Technologies, have been kicking ass, taking names, and generally scaring the hell out of everyone else who wants a share of the computer-music market.

But the Metamucil of technology doesn't settle in the bottom of the glass for very long, especially when audio reviewers are doing all the stirring. (Stereophile thrives only by sowing discontent among hapless consumers. I read that on the Internet, so it must be true.) Thus the folks at High Resolution Technologies (HRT) have been busy in the two years since they introduced the Music Streamer ($99) and Music Streamer+ ($299) USB D/A converters. In August 2010, the Music Streamer II ($150) and Music Streamer II+ ($350) arrived.

Except for their slightly different logos, the new models look exactly like their predecessors: 4"-long (Streamer II) and 5"-long (Streamer II+) boxes of hexagonal cross-section, made of aluminum alloy and painted red or gray. The boxes are all but featureless, having only a USB jack at one end and a stereo pair of RCA jacks at the other. Neither wall warts nor DC-in jacks are needed—the Music Streamers get all the power they need from the USB bus itself.

Inside, the most obvious difference between the old and new models is the use of a single PCB in each instead of a motherboard with a smaller plug-in (as before). However, designer Kevin Halverson says that the differences are many, including a thoroughly redesigned power supply along with newer and presumably better USB transceivers, D/A chips, and other bits. Indeed, I spotted a high performance TI TAS 1020 chip among the various subminiature imponderables in both new models. (The earlier models had used the resolution-limited Burr-Brown PCM2706 transceiver chip.) The new Streamers are claimed to handle sampling rates up to 96kHz and word lengths of up to 24 bits. Further, Halverson says the new models will always play music files at their native resolutions, with no attempted upsampling of lower bit rates and word lengths.

Like the originals, the new Music Streamers were easy to install and to use. They powered up automatically when connected to an active USB bus, becoming very slightly warm to the touch over the course of several minutes. Proprietary software identified each HRT converter for the host computer—in this case, a recent-vintage Apple iMac—after which output-device selection was performed onscreen in a matter of seconds. For audiophiles, such as I, who use Apple iTunes without benefit of a software plug-in such as Pure Music (see Stereophile, August 2010) or Amarra, it's also necessary to adapt to each distinct file type by exiting iTunes, opening the computer's Audio MIDI utility, and selecting the appropriate sampling rate before reactivating iTunes.

If I had to describe in two words the improvements offered by the $350 Music Streamer II+, they would be: appreciably richer. Surprisingly or not, the same must be said of the performance changes noted in replacing the original budget-priced Music Streamer with the $150 Music Streamer II: In terms of sheer degree of improvement, in fact, the less expensive Music Streamer II is the greater success, and the performance gap between the red and the gray converters is smaller than before.

As evidence, I offer the way the Music Streamer II played pop recordings of no great pedigree. Audra Mae's wonderful "The Happiest Lamb," from the CD of that title (ripped from Sideonedummy SD1416-2), is ripe with the trebly sounds of various percussion instruments, which ring overmuch through even the best DACs I've tried. The Music Streamer neither harshened nor softened those sounds, but simply passed them along, with virtually the same degree of unfettered and reasonably natural flow to the music itself. The Music Streamer II sounded slightly less open than the II+, and spatially less "precise." (My sample of the II had an output imbalance that favored the left channel to a very slight degree; perhaps the higher cost of the II+ allows for tighter tolerances in that regard.) Recordings already noted for lacking openness and sonic light—the Vienna Piano Trio's appropriately dark performance of Mahler's Piano Quartet (ripped from MDG Gold 3421354-2) comes to mind—sounded more explicit through the dearer HRT box, but the Music Streamer II got the job done nonetheless.

In fact, although it didn't always satisfy my desire for the ultimate in open, colorful, organic sound—it's hard not to get spoiled in this job—even the cheaper Streamer was enough to please me, absent an Ayre or a Wavelength of my own. That's a remarkable thing to say about a $150 product that also has the distinction of being made in the US. For anyone with a decent computer and a copy of iTunes (or similar software) who has yet to try a USB converter, the Music Streamer II is indeed a no-brainer: Just buy the thing and get on with your (musical) life.—Art Dudley