Hello everyone. I am new to the forum and recently inherited a 2013 Ford Taurus that has the factory touch screen navigation audio system that does not have a factory amplifier. I was very unpleased with the sound so I installed new speakers all the way around, added a sub box with 2 12s and 2 amplifiers(one mono for the subs and one for the door speakers. Anyway since I installed the system, I am getting a high pitched whine from the door speakers, even when the volume is all the way down. I have tried installing ground loop isolators, replaced the ground and even tried rerouting the audio wiring to the other side of the car. Is there something I am forgetting? I've done my own car audio for years and I am also a senior electronics at the City of Dallas. Any help on this matter would be greatly appreciated.