I have a 2002 GT Coupe that I bought 4 years ago that already had an aftermarket radio that uses the Mach 460 system, and it worked great. About 2 weeks ago I was driving home from college and I noticed that all my music had lost its bass. So after some investigating it's only playing through the 4 tweeter speakers that the match 460 has but not playing through the other 4 bass speakers (2 in door and 2 above rear seats). I checked the fuse for the rear amps and it is good. I also checked the connector behind the kickplate on the drivers side and that was fine and had 12 volts of power to it. I'm thinking maybe the amps died or something but can anyone else point me in the right direction as to testing for power to the amplifiers or tell me what they think is wrong?