Which speakers will fill 5,000 cubic ft coherently

In porevious threads I've bemoaned the fact that my Kharma 3.2 FEs don't fill the room, 17 X 23 X 15 ft ceilings with a vertical enough soundstage, as though the speakers are literally too small. I have been advised to raise them,which I have done, , I have told to get taller, line arrays, even given names of custom speaker makers. Any specic recommendations from those that have had, and have conquered, this issue.