I have two of the original HSU VRF-2 10" subs. They are quite amazing in their own right, but I don't have much real estate in the living room and wife says one has to go. So... was thinking I might upgrade to a 15. I'm thinking probably less spl output but would go lower anyway, as the Hsu subs don't go much below 25hz. What do you think? Budget is an issue, but I figure I can sell the 10" subs and put that towards something new.