I have a 97 Limited Edition, my son blew the rear sub and I replaced it with a boxed sub. It worked for about 2 days. As I was driving it home I noticed the bass starting to fade and a strong electrical burning smell, now nothing works in the rear and I have no bass tone coming from the other 4. I think I fryed the amp? Question: can I just change out the Amp or do I have to replace the entire autio system?