Apache, was that really necessary? Your childish response strikes me as the time-waster here. Just couldn't handle being told politely that you did not grasp the nature of the problem? This sort of nonsense is one of the reasons I don't post much around here.
Let me explain things to you in a little more depth. Your recommendation for "more power" was intended to do - what? Radically alter the frequency response of the speakers? Of course it would not do that, but my explanation of the issue makes it clear it is primarily a frequency response issue. Adding more power just might improve dynamics, which isn't what I complained about, but it sure wouldn't fill in the low-mid bass region unless I *also* turned the *volume up*, which I had/have no reason or intention to do.
Manufacturers (good ones at least) voice speakers with the notion of some room-reinforcement of bass in mind. Most speakers do sound 'thin' in an extremely large acoustic space, which is what we have here. Thus, the problem could be stated as replacing the room-reinforcement that occurs in a small-medium room, which means somehow boosting that bass. That means more driver area for producing bass one way or another.
Tvad's idea of going to horns with 15" bass drivers is not bad, as they have so much direct-radiating area that it might make a difference, but I don't think it would really solve the problem completely and is not viable for financial and other reasons.