I'm selling a barely used M-Audio Sonica w/ original box, manual, and cable. It is a very compact (size of cigarette pack) USB 24-bit/96khz DAC (Mac/PC compatible), perfect for desktops or laptops (powered from USB). It has analog line-out as well as optical digital out. It also has SRS 2-channel surround processing (sounds like a crossfeed) and can output Dolby Digital 5.1 from your DVD-drive to your AV receiver. This device does not need a soundcard, just a USB port. The only reason I am selling it is because I got a DI/O and Optimus CD-3400, and no longer listen to MP3s off my work computer.
I've only found it sold from the M-Audio store and CompUsa for $80+tax/shipping. I am selling it for $65 shipped.