Speakers for a large vaulted room?


I have a listening room that is new to me. I have had trouble with my gear in this room and I want to see if anyone thinks the speakers will make a difference.

First, the room is rectangular with a brick fireplace flue that goes floor to ceiling pretty much dead center of the room. from front wall(speaker side) to back wall; a distance of 23'. I sit with my back to the 2 1/2' fireplace with all the empty space on either side of me. The walls on either side of me are 16' apart and only 4 1/2' tall then the ceiling take over and goes to a 12 or 13' peak.

Second, I am using an SP-6 preamp, V70 power amp from audio research and Magnapan IIIa's. I realize that the Magnepans need more power so I wanted to go with PSB Synchrony one's.
sonorous1
It will make them sound louder... not necessarily better.

Come to think of it, they may not even sound louder because volume level drops off quicker with increasing distance from the speaker when comparing a planar line source to a standard cone speaker system.
Volume is what I wanted to solve first, power is an issue for me I only get 70 watts a side, I don't listen loud, which is ideal, but some classical music or albums with a large dynamic range will clip. So the room size and the speakers I thought were my first concern. As I said, I'll change anything besides the amp and preamp.

So, even a more efficient speaker in terms of power needed wouldn't help me? What can I do?