should be fine, I have a pair of Thiel 2.4 in the same size room (11/15/8) and I feel like the room could support more bass than the one 8" driver my Thiels have.
Can you get them out from the front wall a good bit, say 4 feet and sit 3 feet from the back wall?
Can you get them out from the front wall a good bit, say 4 feet and sit 3 feet from the back wall?