Having said all this, can you call a troubleshooter..ie expert electrician who would be able to fix something in your lines and give the tv a dedicated line. I don't know if this will work. Because if you hear this noise in the quiet parts of the movie then there is a problem that will always bug you. Can you somehow TEST a different tv on your system. I know it is a huge job BUT maybe the tv has got to go. First get expert electrical advice.