I'm considering buying a condo, but have to consider soundproofing as a limiting factor.

What's a good STC rating for a home theatre enthusiast as myself? I have an Axiom Epic 80 (no sub, but soon to be an SVS sub), and I don't want to become my new neighbor's biggest enemy the day I move in.

I will only buy a place with concrete floors, but it is the walls I am concerned about. Many places are advertising STC rating 63, which I hear is half decent. Others are saying they use a "Cali" system (?) to soundproof to 69. Is there THAT much difference between 63 and 69? Is 63 sufficient to watch Underworld at a nice volume with an SVS sub?

thanks for all your help.