Hello, new member I am trying to get my system wired in my BMW I have 2 8” under-seat subs, 4 channels all around, and a JL 10w3 in trunk I have a PnP harness to bypass factory amp and provide connection to outside amps having problems deciding how to wire the 3 amps (mainly signal wiring). My 4ch does not have pass-thru signal out-puts