I just put a system in my new truck that came with the KENWOOD KDC-X579 while puttin the rca's in I saw there was 3 different ones. Front, Rear, And another one that I think is non fading. Which one should I use? And does anyone know any settings to make the sub hit harder cuz I was fiddleing with it and it still doesn't hit that hard. Thanks ALOT!.