I'd be checking how the speakers have been wired... Check the polarity. Also check that there's no fader control... I once spent hours re wiring a head unit that was not going any louder than a whisper. Failed to notice the fader was turned all the way to rear, in a car with no rear speakers.
I'd be checking how the speakers have been wired... Check the polarity. Also check that there's no fader control... I once spent hours re wiring a head unit that was not going any louder than a whisper. Failed to notice the fader was turned all the way to rear, in a car with no rear speakers.