For the DAC I'd go with one of the Wyred 4 Sound models. I owned the DAC-2 and it is excellent.
That said, you can buy a Musical Fidelity V-Link USB to S/PDIF adapter for $119 on sale on Audio Advisor and Amazon last time I looked. I was using one to play hi-res (24/96) files off my laptop (to the big rig) the other day and it sounded incredible. From memory, I believe the W4S DAC-2 sounded at least as good and it is rated up to 24/192.
