I have a 93 with the nakamichi system I got it with a blown sub and 3 speakers I'm replacing the door speakers and I'm not going to be using the sub I want to install a amp I already have to power 2 10inch subs my question is does the factory amp power the door speakers or can I just get the cheap harness to hook up to my double din and it be plug and play or do I need to bypass my amp for the door speakers i cant find anything that says for sure