I'm thinking of getting a pair of floor speakers for the front of a home theater setup and for 2 channel stereo. The ones I'm looking at go down to 38Hz with two 6.5" woofers. What kind of bass am I going to get out of those in home theater mode? 38Hz isn't much higher than some subs I've seen. Will adding a separate sub, even if it only hit 34 or 35Hz make a difference? Or do I really need to get one that goes a lot lower? Of course, I'd like to go down to 20Hz, but I don't know if I want to spend the money to get that low cleanly. How low is low enough?