I have a 08 Lancer GTS that came with the Rockford Fosgate sound system, I have the line out converters connected correctly after the factory amp. The rear speakers sound mint, very clear, and loud. The front speakers are muddy not as high frequencies seem to come through. I would just wire my front speakers to the rear but then my gps, and Bluetooth wont work so that is not a possibility. It has been this way since I got the car, but I was thinking maybe the problem is the factory amp? Also I get a engine noise (higher frequency wine) in the front passenger side speakers. The speakers polarity is correct. Also with my volt meter I checked the output voltage on the factory amp front vs rear speaker outputs and the front voltage was low while the rear was much higher. Any help would be appreciated. All the speakers are 100% okay none are blown or defective.