I have a friend who wants to add a sub to his HTS. He is trying to decide between the DD12 and the DD15. When he was in town, he came over and I let him listen to my DD12, and he really loved what he heard. However, his listening room is larger than mine. His room is 28x18x8 (length, width, height). So, he's really concerned if the DD12 will do the job or should he step up to the DD15. He doesn't have the luxury of bringing them home because no dealer in his area has the DD12 or the DD15 in stock. So, eithe way he will have to order the sub. So based on the dimensions of the room do you think the DD12 will get the job done or should he step up to the DD15? To me, I don't see much of a difference between the two when I went to Velodyne's site and looked at the specs. on both of them.