Nemoreborn, I assume the f25 is a rythmik sub? And the xs30 Is what brand? See my profile photos , notice my two rhythmic f25 subs up front . I made DIY'ed the cabinets so they could be laid on there side, Brian at rythmik , had concerns about the amps orientation. He said the amp needs to be up right. They are really articulate subs powerful with plenty of headroom,they easily keep up with my JTR t12's up front. I also have two f15 at the rear. All are sealed great subs.