I have the SBT and am very impressed with the sound from the digital output. With the SBT, USB issues are off the table, and, at least with 16/44 flac files, I have not had a single hiccup (no hi-res files on my server yet). Note that my dedicated music server (VortexBox Appliance) is connected to my home network via Ethernet cable. Plus, the damned thing is fun! I never thought I would enjoy the SBT vs. spinning CDs as much as I do, but once my whole collection is on the server, I don't think I'll be spinning many CDs.
And, oh yeah, the SBT is a bargain!