It's always nice to use what you have but sometimes it's just better to leave some extra things stored in the closet. You could use the 2 satellites as Back-Surrounds for a 7.1. And I suppose you could use the speaker-level inputs on the back of the sub to connect it to the center channel output of the receiver but that really wouldn't be a good idea.
I would sell the 2 satellites, subwoofer and your present center speaker and purchase a better defTech center speaker that would have a better chance of keeping up with your fronts. And even though it sounds like the front towers are putting out plenty of bass a real subwoofer (SVS, HSU, Etc.) will show you that they aren't.
Integrating speakers where they aren't designed to go never works out as well as hoped.Go to the full post