Not the quality of the drivers, but that the specs of the Klipsch driver may not work with the way the JBL's box is designed. It will work, but whether or not it sounds good is going to be anyone's guess.
IMO, the Dayton subs from
www.partexpress.com may do the trick - 300-632 (10") and 300-634 (12"), though they are both only rated to 25Hz, which isn't much lower than the 150.
Can you still return this sub? What did you pay for it?
Check this out:
http://forums.audioholics.com/forums/showthread.php?t=14343