My amp (Lightning Audio B300.4) has a built in crossover. It is a 4 ch amp which I am running 1 sub (bridged through rear channels) and 2 6x9's (front channels), it sounds pretty good but I think I still need to work on the crossover a little bit. The range is 40-400, where should the sub be between the two and where should the 6x9's be? There was also a juice boost, etc. that I'm not 100% sure as to what it does and the manual was not a whole lot of help. I will read it again though, just wanted to get some oppinions.