Room size is about 14 x 16 with a ceiling that peaks around 12' in the middle. Back opens up into dining room with an opening about 9"6" wide (essentially no back wall). I believe that the peaked ceiling, lack of back reflection and slab floor combine to make for very good acoustics, with the added benefit of providing stereo background dinner music in the dining room. The only acoustic tweak I use is a set of four of Echo Busters "Corner Busters" which are positioned on the floor (given that the ceiling slopes up from each of the four top corners). I also hung a tapestry on one of the side walls and put a sofa on the other.
The Merlins might have some trouble in a much bigger room but they sound large indeed in this room with the BEL amps.