That room is much smaller than mine. I'm 19 feet by 33 feet. In that size room you may be fine with a good 200 watts per channel. B&W reccomends 250 watts or atleast thats what they told me as a minimum for the 803d but I'm sure they won't try to talk you out of buying. When I was going to get the mcintosh mc275's in mono parralel, they told me I'd be better with the 803S and that they reccomend 250 per on the D's. That is where I'm coming from on this. They will be great either way with the 200 I geuss but would be better with a little more, but then again what wouldn't be. With the room size should be fine though.
good luck
beerdraft
good luck
beerdraft