I think you are going to need to add a subwoofer for reasonable sound. I also think one of the biggest concerns will be getting reasonable sound pressure levels in such a large room with most in ceiling speakers. Theil makes a nice ceiling speaker with directionality, but it's rather small. I think for a room that size it might not be appropriate. Energy veritas I believe have some that are directional and probably a bit better in terms of power. B&W make some really nice in wall (could be used in ceiling though) in the CTX line that have the ability to point the mid tweeter to a pretty decent degree. These are quite expensive though.