Ground loops are the bane of home theatre enthusiasts. A ground loop occurs when current flows through the ground path of a home theatre system. The only way this can occur is if the ground potential is different at various ground points in the system. This usually occurs when a system is plugged into cable television, since the ground potential of the cable may be different than the ground potential of your house's electrical wiring. The symptoms of a ground loop is a persistent 60 Hertz hum. Getting rid of the ground loop hum requires installing an isolator.
Unscrew your cable from your cable box.
Attach the ground loop isolator to the end of your cable. This will block the 60 Hertz signal from passing through the cable and into the sound system.
Screw the cable back into the cable box. The ground loop will be eliminated.
You can use old television antenna baluns as makeshift ground loop isolators. They are quite a bit cheaper than ground loop isolators. A balun is a tiny transformers, and the 75 to 300 Ohm baluns used to connect antennas also does a good job of filtering out the 60 Hertz noise.