Audible Hum

P.S. Checkout the chat topic "AC grounding" on the same list as your post

I had the same problem with different components, but the fix was the same. I put a cheater plug on my preamp and my system has not had any hum problems since.

One thing I recently found helpful, is try unplugging the inputs to your preamp to see if it goes away. I had my TV connected into the aux input, TV's are a great culprits of hum because there antennas are grounded. This solved my hum problem, and it wasn't present with the previous preamp.

Turns out I had a dual problem. Primary one was cable TV ground problem. Tried to resolve it by rewiring the cable box, but the morons have grounds to the electrical system, gas pipes, etc. Ended up buying an inline device by a company called Viewsonics from a local audiophile store for $30. Their Web site is www.viewsonics.com, though I didn't see this filter listed. The other problem is was sort of mismatch between the amp and preamp. In addition to calling the pre's manufacturer (still waiting for a call back) I floated the ground on the pre and the noise floor is vastly quieter. Finding the problem, as Bob said, involves starting at one end of the system and working back to the other end.

Thanks to everyone who posted an answer. It turns out that the cheaters plugs did the trick!!! Thanks again.