humming in my system

The ubiquitous ground loop hum.

Do a search of the threads for "ground loop", "hum", etc.

Many suggestions and techniques will be found.

As Tvad has said, this has been discussed many times before, so perform a search of the archives.
From what I can recall, usually the main culprit is cable tv. If you have cable tv, disconnect it and see if the hum goes away. If so, there are ground loop isolators out there that will help you.

Cheers,
John

www.lyrics.com

Sorry I could not resist.