I can only repeat what is said above - Isolate the CATV-in from the rest of the system first.
I use the Jensen VRD-1FF, but I am sure there are others.
Once that is done, hook every component up to the same single electrical outlet.
If you still have hum, start connecting and disconnecting everything (both the electrical plugs and the cables) until you can find the source of the hum.
I use the Jensen VRD-1FF, but I am sure there are others.
Once that is done, hook every component up to the same single electrical outlet.
If you still have hum, start connecting and disconnecting everything (both the electrical plugs and the cables) until you can find the source of the hum.