Long time lurker, first time poster. Here is my situation. I have a full polk audio speaker package without the subwoofer which includes: Fronts: RT35i Center: CS245i Surrounds: f/x300i This worked great for my apartment. But now I've recently moved into a house which demands more base. So I'd like to get a subwoofer now which will work well with these speakers. But the bigger problem is I'd like the subwoofer to work well with the future speakers I plan to replace the polks with. For instance, I'd like to get some power towers for the fronts and probably a bigger center channel, probably from a higher end brand. Is there any hope of finding a subwoofer that will work now and in the future? Or is it a futile effort and should I just look for something that works well now, and buy a new sub when I upgrade the fronts and center? Thanks in advance.