Jumping in here, because I was also interested in an external DAC (mainly for the ability to switch between headphones and speakers without getting under my desk, and because the noise on my speakers is ridiculous).

Gotta ask: does your computer have some other form of digital audio out, such as S/PDIF or HDMI? Could you not run that into a standard amp, rather than using USB to a DAC? You'd get more options, and they seem to be slightly cheaper.