The PB13 would no doubt have more output in the deep bass, I'm guessing anything under 30 hz. If the sub is for movies, that is something to keep in mind. But the Sub15 is no joke, if your application is music, I might swing for a Sub 15, if it was the same price. There are other subs already mentioned that I would rather have than either, FW 18.0, Hsu ULS 15 dual drive, Seaton Submersive, each of those costs a bit more than the $2k price of the Pb13. You might also look at the JTR Captivator, that has received a lot of positive attention, and would likely have more output than any of them.