I am installing a 12 inch Soundstream CG-12X sub and a Cerwin Vega XL 300.1 amp to a 2000 Dodge Caravan. I am running into difficulties because I have to keep the stock deck in. I was going to try running from one of the back speakers to the sub but then I have no way of turning on or off the bass without affecting the whole speaker system in the. Has anyone wired through a stock system of any car or truck? Can anyone please help me sort this out. Basically I need to be able to turn on and off, down and up the sub because it is a shared van and the last thing the other driver wants is to be seen driving down the street with oldies pumping. Any products or wiring tips would be greatly appreciated, Thanks in advance!!