".... It's a 19 x 11 room and it's for a stereo, not a home theater system. We listen to mostly rock of various sorts, R & B, some jazz, and a lot of acoustic music."
For $300 or less, if I were you, I'd keep it 10" or below.
* Do you have any good samples on instruments/acoustic that I could look it up on YouTube.com?... I like something that could put me into sleep.