active vs passive speakers

I am looking at the Gradient Revolution speakers and I can't quite grasp what the active version does. In short, what is an active speaker?

csmithbarc10-28-2008 2:24am

csmithbarc OP Details Discussions Posts This discussion Message User 29 posts 10-30-2008 at 02:28am Copy Comment URL Report Comment Edit Delete so do you need to own four amplifiers...two per side?