Factory Amp where is it?

I have a 96 bronco that had premium sound I have since replaced the head unit and front speakers and used a wiring harness that does not by-pass the amp. A freind told me to by-pass it because it was not gonna give the right sound since I have a radio that is internally amplified.And I have noticed that it gets distorted way before half power on the volume.I want to find the amp and by-pass it he says he knows how to do this if I can find the amp that way I won't have to annie-up for another wiring harness that blocks the amp. Can anyone tell me where it's located on a 96 EB.