I'm thinking about how a false wall would effect the audio sound?

Reason I'm thinking about a false wall is with my tower speakers 20" deep and wanting a front projector, i feel that the towers will look out of place between a screen mounted on the wall.

I think when you put a box around the speaker the bass increases. If that is true would a false wall 2-3 feet deep have the same effect. would the false wall effect anything else?

Thanks
Greg