I currently have a 400watt 4 channel hooked to my 4 speakers. I like the sound but I want a bit more bass. I have a extra 200watt amp and a 200watt 10" sub. Whats the easiest way to run power to the second amp? Would I need to run another 12v through the firewall? Or could I bridge the same line and ground off the other amp along with the on/off signal wire?