Postby dsbenson » 11 Feb 2014 17:36
AirPlay does AC3 passthru with Mavericks. You can see this in action with movie files. I'm not sure if this works with VLC, but it works with iTunes or apps like Beamer. With iTunes, the 5.1 audio needs to be a second audio channel, encoded as AC3. With Beamer, it can be a primary audio channel (and I believe can be in a 5.1 format other than AC3).
However, I can't find any app including VLC that can stream *audio* files with 5.1. I wish VLC did. It seems clear that AirPlay can handle this because it works with video files.