I use a Klipsch DD5.1 system on my TV for surround sound. It works ok, but lately I don't notice hardly any sound on the rear speakers. They are hooked up and work cause you hear sound slightly out of them and the test tone works. I have it hooked to my satellite dish network receiver thru the optical cable as well as the regular a/v wires and still nothing. What could be the problem?? I'm about ready to ditch this for a different surround sound receiver.