In a room that size you might not need to worry about a sub. I think you can find any number of good, stand-mount speakers that provide sufficient low end and will sound more coherent than trying to integrate a sub with the satellite speakers. I have a room just a couple of feet larger than yours, and I've found a decent pair of bookshelf speakers to be more than enough in terms of bass (and sometimes even too much).
Just a thought,Scott
Just a thought,Scott