I remember some cases where the speaker-cables acted like HF antenna's.
Most of the time they are unshielded and long.... just like open dipoles
So removing/checking them could help.

Low-pass mains-filters block HF signals captured by the electrical wiring in your house. I purchased some of these for my neighbours at the time I operated my HAM-radio station.....and they did a good job!

So, don't focus on the inputs only because HF has many 'doors' to come in.

Roel
PA3AGX

[This message has been edited by Roel (edited 02-17-2005).]