woofer to room length ratio

Is there a recommended ratio in determining woofer size to room size? I am considering a soffit mounted three way monitor (15"/5"/1") in a 19' x 16' x 10' room. Most of the the music covered would be acoustic/rock with some midi tracks. Would this be too much speaker for the size of room? If so, what would be a better size to consider? Thanks! :D

I think going with a 12" driver is more than adequate

Thank you, Bryan :D