I was very interested in the Pi Seven-18 Professional version for it's deeper bass response myself. While I think I could have accomodated their size in my room (16x22), they are considerably larger than the 15" version. I took a chance and went ahead with the smaller 15" pro version. I'm not completely finished building the midhorns yet, but last night I finished the bass bins and hooked them up full range to 200 watt monoblocks. I'm very pleased with the depth and range that the bass has, and I'm also surprised how well the 2226 covers the mids and highs when used full range. I'm used to Von Schweikert VR4s Gen III SEs that are capable of 16hz. The Pi 7 may not go much lower than 40hz, but the quality and quantity of output at that level has surprising impact and articulation.