I have what I believe is an acceptable setup at home (Denon AVR-X1700H and Apple TV like the OP, a decent Sony display, 7.1 speaker setup, but the plethora of audio coding options completely mystify me. I know this is a me problem. I'm hoping in the new year to watch more movies with the family and would like to make better use of the surround system for sci-fi and action movies but for whatever reason I have no idea where to start.