and there's no issue with tapping into the wires using no line driver or something? don't want distortion or weird out the stock radio by loading it with more wiring.

would this work as well?
pull the radio, find those two or four wires going to the back of the rear door speakers, cut and splice in this line driver? then reconnect the factory speaker wiring to the output of the line driver, like the pic shows?

i got it covered what you suggested, and will probably do that, thanks for the info guys.