guys need some help here, i just got a new jvc headunit with a wiring harness from crutchfield that has 4 rca plugs but anyway i installed everything to my factory bose system. the only problem im having is that i cant control the bass/sub from my new HU. there is a rca out on the HU for a sub but i dont know where to tap into on the bose amp or sub to get the new HU to control my bass. i dont even know if its possible. any suggestions. i like how the system sounds im just not getting any bass and it sucks bad. i have a 03 B6 with the symphony II system and bose amp.