A simple small footprint PC with HDMI out plus storage along with Foobar2000 (free) and you're off. Using DVDA extractor can also help you pull 5.1 and 4.0 (and even 3.1) from DVDAs and have them as nice and easy MCH FLAC. I still have the Oppo and I will still be upgrading to a new one soon enough, but for my own needle drops from the Surround Master and for converting my existing archive, it really works and it works well. So well in fact that I am adding the e28 Exasound MCH DAC in the new year. The set up even allows me to run stereo from the 3.5mm analog out of the PC into the stereo switch that has the Oppo and the record deck connected so I can play QS and SQ encoded stereo FLACs or CDs through the Surround Master with total ease. Foobar2000 let's you dynamically change whether you are outputting 5.1 or 4.0 via HDMI or whether you are using the HD stereo out.
Thanks for all the great info!
(Apologies for going off topic but while I've got your attention on this subject..!