Got Dolby 5.1 out of Mac mini with iTunes!
All you need to do is go to Applications then Utilities then to Audio MIDI Setup you need to change Digital Out to Encoded Digital Audio that will put Format 48KHz automatically then exit. You then go to a Movie SD or HD and or TV Show select Surround you see the Dolby Digital light up on your receiver! This is a System Output so I been enjoying TV Shows and HD Movies like Casino Royale! Pics of my set up is below!