I have recently joined the ranks of those able to play 5.1 FLAC files, and it has been REALLY exciting for me. All my music files had been stereo ALAC files stored on an OWC 6TB HD connected to my Mac Mini. The Mac Mini was then connected to the Oppo 105 via USB, which acted as my stereo DAC, and files were played back using JRiver MC. But from what I understood, the only way to use the 105's excellent multichannel DACs was through physical media. Finally someone on AVSForum told me that if multichannel files came into the 105 via ethernet through a DLNA, they would be output by the Multichannel DACs! While I understood very little about DLNA (still do), I found that JRiver MC automatically generates my library as a DLNA server. Now I am in heaven being able to store 5.1 FLACs in my server alongside the stereo ALAC files.
I never realized how much the act of retrieving physical media from my shelf and loading a disc into my system was keeping me from enjoying the music (especially those enormous King Crimson sets). But now that I'm able to play any of the Yes or XTC surround releases at the touch of a button, I've really been diving in. The only issue is that the Oppo cannot do gapless via DLNA, so there is a significant pause between tracks (which is murder for live releases). Hopefully that will be rectified in the near future. But this has totally changed my musical life, and made me really excited to build my library by ripping all my 5.1 discs.