I just bought the Lord of the Rings: The Two Towers, The Complete Recordings. It comes in a 3 cd and 1 DVD Audio Disc package. My system is a HTPC. My pc is hooked up via optical to my Yamaha Receiver, an HTR 6080. I popped in the dvd and started up Theatertek and the dvd plays. The Digial Dolby light on my receiver comes on. So far all good. The question I have is how do I know if I'm getting DD 2.1 or DD5.1?