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I just bought a 42" Samsung Plasma and I'm having trouble getting the surround sound to work when watching Hi-def channels. I have a Denon AVR 3300 receiver and I have that connected to a Motorola Cable Box using an optical cable. Problem is, there's no sound. I was told by someone that I might have to assign the TV to the optical jack. I have no clue as to what I'm supposed to do. I tried reading the manual, but got nowhere. Everything else works perfectly - HD is crystal clear, DVD player sounds great in Dolby Digital - but I must be missing something obvious. If anyone has a Denon receiver and could walk me through it, I'd really appreciate it. BTW, the cable is a brand new Monster Cable Ultra 600 Fiber Optic and it is lit up on the end so it seems to be working.