Need to check the specs of the sub too. If you build your box to play lower than what your sub can handle you will torch it pretty quick. That's why I never understanf why peolpe buy those pre-febbed boxes, they aren't made for your sub 99.9% of the time. Doesn't matter what kind of box you build, if it's built to the proper specs it will sounds good. How long have you had the sub? You might be able to take it back and get it swapped out for a new one from the place you bought it from. Sorry to say but Pioneer subs really aren't made to take to much abuse, if you get another one I wouldn't try to push it to low again.