Treble / Bass Balance Issues

[Berlusc0ni]

Alright, let me start by saying that I'm new here, so if I'm posting in the wrong area, please feel free to direct me to where I should be posting.

Now, I'm driving a '96 Grand Prix GTP that I picked up a few days for $170. One hell of a steal, I might add. Very little problems with the car and it's in great shape. New tires, brakes, gaskets all around, etc.

Anyway, to my issue. I'm using the stock head unit and everything works flawlessly except for the rear speakers. The rear right speaker is 100% treble, no bass at all and the rear left speaker is 100% bass, no treble. Both of the speakers are brand new, they are 220W Pioneers. The front speakers balance perfectly and (I can't remember the wattage, I literally installed them yesterday...) Sony X-Plods.

I've fiddled around with the treble / bass / balance / fade knobs and nothing has remedied the issue.

If anyone could point me in the right direction as to solving this problem short of going aftermarket or picking up a replacement, I'd greatly appreciate it. I have a fair understanding of electronics and am okay with pulling things apart and running tests.

Thanks in advance!

[1LoudGrandPrix]

try swaping the wires (L&R) and see if the samething happens fyi i would just put in a new HU and run your own wires to the back

[Berlusc0ni]

I've considered an aftermarket head unit to get USB functionality, but I really don't want to lose steering wheel controls and I absolutely hate the look of other head units. I'm trying to keep the interior as clean as possible.

Are there any other stock head units that will fit this car that have auxilary inputs / outputs? If that's true, then I'll just call up the local part yard and have them add it to my list of parts.