So im gonna use my old http://www.woofersetc.com/index.cfm?...product_id=483 amp to power my fronts i just hooked it up to my backs and it was so much better then my Hu sounded really good but it sounded loud with no gain on,, should i use gain i'm gonna be using a 15 fi bl for bass...can i use gain what is the downfall im gonna bridge the amp??