I finally picked up a battery isolator for my stereo system, It will allow me to charge 2 batteries off the alternator without frying it and also it will only draw power from the secondary battery for the audio system and the main will stay charged for starting/etc.
here are a few pics, I got this at a junk yard out of a ambulance for $2 ! and they sell over $200 .

 

2 fricken dollars?????? Wtf man... That is an awesome deal for such an awesome little gadget you lucky bugger.