OK...I just had to revive this thread cause I finally found the problem
Maybe this might help someone later on...
I have since tried everything. Had mediums come to my place = No ghosts
placed garlic in every corner of the house = No cure
No electricity close by my house...dug all around my house...no bones. no electrical wires anywhere.
Had scientists come to my house...they did tests for 3 days and couldn't find anything...
All kidding aside. I finally found the problem.
I decided to remove the ground connection to my water pipe and BINGO no more humming in my speaker (When speaker IS NOT CONNECTED)
My right speaker is close (about a foot away) from the incoming city water pipe.
It's been disconnected for a few months now and NEVER got a hum since!