HRT Music Streamer II

Until recently, USB audio adaptors relied on a default transmission protocol called adaptive-mode USB audio. In short, the essential clock timing signals used in digital-to-analogue conversion are derived from the computer. Like the S/PDIF interface used in hi-fi equipment, a clock recovery system recreates the timing pulses required to reassemble the binary stream correctly.

Rather than passively receive whatever the computer dishes out, asynchronous USB mode devices such as High Resolution Technologies’ Music Streamer II take a more pro-active role, telling the computer when to send music data packets.

In the case of the Music Streamer II, its digital receiver is actually a transceiver—able to transmit instructions back to the host as well as receive data. After this, a Burr Brown PCM1793 24-bit/192kHz D-A chip carries out the conversion from digital into analogue music. In use, it works at 24/96 resolution, a true audiophile standard.

Externally, the Music Streamer II is an innocuous lump of extruded aluminium in an unassuming red finish. On one end is a USB port, on the other, a pair of gold-plated phono sockets.

To set up, just plug into a Mac’s USB port, and connect to your music system’s line-level inputs. Power comes from the USB bus. Configuration just requires selecting the Music Streamer II as your chosen sound output device from your Mac’s Sound system preference.

The Music Streamer II was capable of great subtlety in playing music. It impressed most with its freedom from digital grit. This DAC is a real smoothie, yet one that doesn’t over-compensate for brightness by smothering the sound in cotton wool. Music is heard relaxed and flowing, with precious little grain to intrude.

Playing acoustic jazz, for instance, the thrum of a simple repeated note plucked from a double bass had believable presence, showing more depth below and more overtones ringing out above. The layers of the quartet’s instruments made more musical sense here; particularly left-hand chord shapes under the right-hand melodies of the central piano.

For reference, the USB input on a Cambridge Audio DacMagic ( ) rendered the song with a muted thud of a bass line, while its splashier cymbals were more like you’d hear from a compressed MP3. Meanwhile the Music Streamer II could bring out the lucid, soaring saxophone lines with a naturalness that rivaled top-tier analogue reproduction.

Stereo imaging from the HRT unit was noteworthy—without a steely midband overriding the sound, instruments sat more naturally in left-to-right panned perspective.

Macworld’s buying advice

The HRT Music Streamer II is a great-sounding digital converter for your Mac. It’s a great investment for its big, natural sound, superbly bringing to life the music in your digital library. And it costs significantly less than the DacMagic.