I am getting either two 12" fi q's or two 12" fi bl's and i was wondering if the rockford fosgate t.1500 amp is enough to power them and if the bl's are a big difference over the q's and how loud they are. I care about sound quality but if the q's are a lot quiter i would rather just go louder and get the bl's

There is a lot of information you left out in your post to help you make any sort of informed decision, but based upon your quest for a louder setup, why don't you just port one BL15. No need to put two on that amp.

If you are comparing the two, you probably aren't a Q buyer.

i went from a pair of q 15's on a crossfire vr2000d to a pair of bl 15's in the same box. had about 1100 watts per sub on that amp. the q's were about the same, or a little louder.

once i put an american bass vfl 200.1 on the bls though and gave them about 1800 a piece, they really came alive.