Does the sound go away when you unplug the coax cable and just leave the AC power plugged in? Is it a low rumble bass sound, or more of a hum like a transformer makes?
Ground screw was removed long ago to stop the ground loop hum. The sound does not stop when I unplug the sub cable. The only way to stop it is to turn it off or unplug it. The sound is a lower sound - not like a 60 hz hum. Difficult to describe. It is like the sound of machinery operating far off in a big building. Like background noise. Correct me if I am wrong, but it should be silent when nothing is on? At any rate this is my third amp on the 500.
