Samgar2, You can't go wrong with either speaker but with the size of your room the 15A's would be best. I had the 15A's in a 18 x 24 room and they sounded awesome. The 15A's have a bigger sound which is why i bought them and I liked the way they look better then the 13A's. However, they are a big speaker and my wife said "x!@#+^!" when she first saw them but learned to appreciate their modern aesthetics. In your case bigger will be better.
IS THE MARTIN LOGAN Renassance 15A worth the $10,000 higher cost than the Expression 13A
Thinking of buying a pair of Martin Logan's electrostatic speakers. I heard the 15A and loved the sound. They are $10,000 a pair more than the 13A. Is the difference worth it? Has anyone ever compared these 2 speakers?