My 2002 5D has the Prestige audio (I believe because it has the Subwoofer in the back, 4 doors, 3 channels on the dash). Since the radio had been messed with, I had to pull a matching Prestige amp from a yard. Plugging it in, I get only the 3 speakers on the dash and the sub putting out sound regardless of Fade setting. In fact, the center speaker on the dash is by far the loudest.

So for testing, I also get my hands on a Premium amp. Simply plugging it in, I get output from ALL the door speakers but not the subwoofer (no surprise on the sub). But it does seem to be driving everything too hard even with the bass turned all the way down. I'm sure you can imagine, I'm trying to get all the speakers to work and sound decent but I could live without the subwoofer.

Does anyone have any explanation for why this might be behaving this way? I will say, I had to re-install a stock radio after the prior owner had made an abomination of the stereo. I would love to hear anyone's explanation/theory as to why the Prestige is only outputting to 4 of the 8 speakers while the Premium amp is outputting to the 7 expected speakers. Thanks!