OK, here is my dilemma. I'm considering purchasing one of the new SVS 25-31PCi subs. I would be upgrading from a 7 year old Mirage BPS-100, which is a bipole sub with two 6" woofers ported with a 100 watt amp. What I would be doing would be giving my Mom the Mirage for her HT (she presently doesn't have a single sub at all) and I would use the 25-31 for my HT. I rarely listen to movies within 15 db of reference. I live in an apartment and can rarely if ever "open up" my system. I do plan to move into a primary house in the next 12 months, but my question is this. At low volume levels (15-20db below reference), what dissernable difference will I perceive between the SVS and my Mirage? I'm actually pretty happy with how my Mirage integrates with my main speakers for music and I am wondering if the "upgrade" will be marginal at best. I'm thinking this might be more a case of "upgraditis" than being altruistic and doing something nice for Mom Thanks for the advice.