HRT Music Streamer Pro USB D/A converter
But the second big wavereally a tsunami nowto wash ashore was triggered by the earthquake of computer and Internet audio, which has also shaken apart the music-industry conglomerates as we knew them. Several well-established audiophile brands, and dozens of newcomers, have jumped up on this second wave, learned to harness its energy, and are riding it in.
High Resolution Technologies jumped on a couple years ago, pumping out one product after another, all tightly aimed at the person with one need: to connect a USB-endowed computer to an audio system. Art Dudley and others have covered the first products released by HRT, and now the company has added to its product line a Pro version of its Music Streamer, which sports balanced circuit design from tip to tail.
Housed in the same simple, functional, six-sided case of extruded aluminum as HRT's other products, the Pro is painted a bright blue to distinguish it from the Music Streamer II (red) and Music Streamer II+ (gray). At 5.6" it is also a tad longer than the others, and includes a single B-type USB 1.1 jack centered on one end, and two small, fully balanced TiniQ output jacks on the other. More about these special mini sockets later.
As with the other HRT Streamers, there is no external power supplythe Pro gets its juice from the USB bus. Also like the other streamers, it provides a completely isolated path from computer to audio system, runs balanced, and its asynchronous USB input handles data rates up to 96kHz and bit depths up to 24. It works with both Macs and PCs and runs slightly warm to the touchmy trusty Mastercool Infrared Thermometer pegged it at 96.8°F after several hours' playing time.
Finally, like the other Streamers, the Pro is attractively priced ($449.95). But it has a higher output4V RMS, or twice that of the other products' 2Vfor compatibility with professional audio products. My plan was to hook up the Music Streamer Pro to both my balanced consumer preamplifier and my pro recording system, then compare it, with both balanced and unbalanced connectors, to the other balanced, professional DAC I had on hand, a Benchmark DAC1 USB, whose conveniently adjustable balanced output levels meant that I could match its output to the HRT's.
Getting ripped . . .
Before getting down to listening-test business, I decided to freshly rip several recent and back-catalog discs from the ECM label. My main computer for these tests is a late-model, 2.66GHz MacBook Pro with 4GB RAM and the standard-issue hard drive.
Since reviewing YBA Design's WD202 DAC and headphone amp in the June 2010 issue, I've been playing with various combinations of ripping and playback software, and have narrowed the choices down to Apple iTunes rips played by Sonic Studio's Amarra Computer Music Player 2.0 software for AIFF files, or FLAC files ripped with XLD and played via Songbird 1.8.0.
For this review, using only the Music Streamer Pro as my DAC, comparing iTunes/Amarra to XLD/Songbird revealed few obvious differences, and the differences I did hear were subtle and often fleeting. I must admit that, having XLD's track-by-track error log (see sidebar, "Ripped") is rather comforting (no errors were noted for the discs used in this test), but I'd be hard-pressed to declare a winner unless you prefer FLAC, which iTunes does not support. Running Amarra 2.0 with iTunes 10 does seem an improvement in sound over my previous Amarra 1/iTunes 9 setup, but the difference was not as noticeable as comparing DACs. Still, overall, I preferred the Amarra/iTunes presentation, and stuck with that for consistency.