More than likely the receiver. It might need to serviced or cleaned.

A simple thing (perhaps a temporary fix) is to try WITH THE RECEIVER TURNED OFF, work the volume control back and forth several (10-20 times) times from min to max point.

ROTATE THE RECEIVER VOLUME CONTROL BACK TO MINIMUM, turn on your equipment and play some music at your desired listening volume.

I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne