Currently have a fairly small sub, and am thinking about getting the Sony SAWM40 that everyone is raving about. If I do, I'm not sure what to do with the old one. It's not going to be worth much as a resale, and I don't have a second system to hook it up to (yet). Is there any advantage to hooking both the old and new up to the system? I know lots of people run dual subs--do the same concerns about matching speakers (brands, makes, specs) apply to subwoofers?