Thanks for your inquiry. Much of this depends on your listening habits, but in a small room your receiver should be able to get the speakers to pretty loud levels. The sub down the road is definitely a great idea as the 4Bs don't really have any bass on their own, however I'm sure you'll still love the sound of them.
Thanks for your interest!
- Oliver
Oliver Amnuayphol
Home Theater/Audio Guru
Aperion Audio