If you can afford it, use two subs. I've been thru two REL subs. The Storm II and Stentor. They are really good with music. I needed two subs to even out bass response and "pressurize the room"! I ended up with a pair of JL Audio subs. If you adjust the subwoofer correctly, it fills the room properly. Bass isn't soft at a live event, it makes its presence known. Ever hear a kick drum or Timpani live?
How to connect a subwoofer into a mono block system
I'm interested in adding a subwoofer into my audio system. I have a new Audible Illusions M3B driving Welborne Labs Laurel Iix ultimate mono block amps and ProAc 50 Signature speakers. I've been confused by material on the web as to how to do this so as to insure that the subwoofer is seeing exactly the same signal that the ProAcs receive. Any recommendations, both as to how to best do this, but also on subwoofer choices?