I got my SVS 25-31PC+ just a couple days ago. I spent a couple hours last night calibrating it. My impressions on this sub is that it's not excellent but awesome for HOME THEATER. It will go VERY low, VERY hard. Even though the cut off is supposed to be 25hz, it will play lower and harder than my old Paradigm PS-1200 that was supposed to go down to 21hz. I debated between this sub, the Paradigm PW-2200 and the HSU VTF-3 MK2.
As far as music played through this sub... well, I don't know. I think anything above 50hz better be handled by your mains if you have this sub. I even setup my receiver (a STR-DA4ES) to cut off LFE for the sub at 150hz and set the sub to 110hz and still feel it weak when playing anything above 50hz. It's almost like this sub likes to "thump" you but not really interested in playing 50-100hz bass notes. I could see this sub as a perfect match for a big front speakers. Definitely not a match for my mini-monitors as fronts. I play movies about 90% of the time on this setup so I'll keep the SVS. In retrospective though, if I played at least 60% music, I probably would have gone for the HSU or even the PW.
Anybody with this sub or setup? I'm pretty sure I'm not doing anything wrong but I'll welcome any opinions.