FWIW, I can sympathize. It's hard to look at numbers on a paper (or computer monitor) and figure out how much better something will be. The only perspective I can give is this: as mentioned, each 6dB increase equates to a doubling of acoustic pressure. At the lower frequencies where a subwoofer is operating, we're talking about sound we can feel as well as hear. So if your current subwoofer is like a twenty pound plate on your chest, assuming Tom's expectation of 4X-6X the output in the deep bass is correct (and he's unlikely to be full of it; there were measurements at AV talk on your PS1000, but the images with the data seem to be gone now), then you'd be looking at an eighty to hundred and twenty pound plate on your chest by comparison with the XV-15.