Sure, you soundproofed the home theater. Your family can sleep through the night even if the volume is cranked up to 11. However, you probably didn't install curtains or the right kind of carpet in the room. By putting soft fabrics within a home theater, you can reduce the amount of echo and improve the experience. Here's how.
Hang Heavy Curtains
These curtains don't specifically have to cover windows. They can simply be wall hangings or hang on both sides of the screen to create a more theater-like experience. Their presence will absorb some of the sound being broadcast by the speakers and create a more thorough audio experience; rather than having the sound echo from the walls in a space not designed for great sound quality, you dampen the vibrations and only hear the best parts.
Lay Lush Carpeting
Putting in great carpeting serves two purposes: one, it feels awesome to walk on barefoot. Who doesn't want to enjoy a home theater in comfort? Two, it serves the same purpose as the curtains. The mass of the carpet and the thick fibers it holds will absorb excess sound vibrations and not only keep the home theater from disturbing the rest of the house but also improve the way everything you hear on screen sounds. Rather than listening to the echo of an explosion while someone speaks, you can turn the volume up and hear the movie as it was intended.
While many people balk at the idea of reducing sound levels, most homes are not designed for great sound quality. They aren't concert halls, after all. A few simple additions in the form of a nice carpet or rug and heavy curtains can improve the overall experience of a home theater. Even if you didn't do this during the home theater installation, they can be added later.