I think we're going to need a little bit more information about your system; but first make sure all your speaker leads are properly connected to the amp or reccy as well as the speakers themselves. Then, check a few of the inputs-do you have sound on the tuner but not the DVD (or vice versa)? Have you properly set up the system to include a center channel, etc.? It's kinda hard to trouble shoot this as it stands...
Bryan...so tell us about your system, then...