[phantom dually]

Try a few things with the ground. If you have the amp screwed to metal of the truck pull the screws out and hold the amp off of all metal. Make sure it is all still hooked up and see if the sound goes away. If it does use a few plastic gromets and space the amp off the metal area just a 1/8" or so. If that is not it try a small length of wire and hold one end to the radio chassis and touch the other to the exposed jacket part of the RCA or even to a grounded part of the truck. Try this at the amp also. Grounds are very critical as said and alot of people never hook the ground wire up securely and the unit will pull a ground from the antenna wire instead. This could be a reason you are getting fuzzy reception also. Let us know!!