Anybody ever hook up an aftermarket system (amps, speakers, sub) to a factory head unit WITHOUT LOC's? Correct me if I'm wrong, but if you use an LOC, you are converting a signal that has traveled through the factory amp. Wouldn't a low-level signal right from the HU, before the factory amp, be best? Any diagrams available? Or wiring harnesses? I have a 2000 Tahoe, non-bose as far as I know, with sub.