Same thing happened to me. I took my subwoofer in to Circuit City and it tested ok. Bought a new cable and came back home and hooked it up again. Still no sound. Called a guy who repairs amplifiers and asked if it was possible my amplifier. Turns out it probably is. The sub woofer is on a separate circuit and costs about $175 to repair or replace if that's the problem. At this point wold rather spend the nearly $200 on a new amplifier. Will be checking around.
Donald Dickerson, February 2006