I've made a couple of sealed boxes for single 10" subs but what if I wanted to put 2 subs in the same box? Would it have to be twice as big? Would it need some kind of partition in the middle? I'll be making this out of fiberglass. I've seen a couple of sites where people put 2 subs in an enclosure but how do they know if it's the right size? On another note, what would sound better 2 10's or 1 12". Both would be sealed.