if you want to listen to cable over your home theater speakers, you need to input the sound signal into the amplifier (or receiver) instead of the television. the way i have my home theater hooked up is i hook the cable line into my tv, and theres red and white audio output jacks on my tv that i connect to the inputs on my receiver. so i turn the receiver to that input (video1) and turn on the tv. the audio is sent to the receiver and amplified to play over the speakers instead of on the tv speakers. if your cable box has audio outputs, just pipe those into the inputs on your reciever.
