Ive had a 540R for a few years now. Love it - just wish it had some more facilities. Anyway, one little niggle is that I have many files (which I play through my Dune media player) that have AAC multichannel soundtracks. The media player is connected to the 540 by optical. However, the amp does not pick up the multi channel track. I can only get any surround effect by selecting pro logic. Can anyone please advise?