What stereo do you have? Mine is an RCA mp3.
I have a cd cleaner disc that runs an audio program that tests all the speakers as part of it's process. You can watch on your TV while it does it and troubleshoot all components.
I suggest you do that as a next step before taking stuff apart.
2003 Tradewinds LTC, Dynomax Chassis,
350 Cummins, 2008 Lexus RX400h, 18' PJ Trailer