I got an HRT Music Streamer II for my parents Mac Mini. Just needed a cheap DAC and wanted one that didn't need a power supply. In theory, this DAC fits the bill. In practice, that's not the case. For anyone out there considering the HRT, be forewarned that you very likely will need to run it off a powered USB hub. It appears to simply draw to much power to run reliabily out of a 'puter's USB ports.
There are a bunch of posts about this on the internets, but I figured I'd give a heads up here, too.