That is a big set of speakers for a fairly small room! I had a pair of Maggie 1.6QRs when we moved some years ago and I tried to use them in a 14 X 15 room. They just didn't work well and I sold them.
And squareness doesn't help. My 2 cents is that your room is likely a bigger problem in terms of the placement of instrument imaging than your power amp. Not saying a better amp might not help, but probably is not the major issue.
The post above suggesting a room analysis is a better start, IMO. The next step would be acoustic room treatment. Only then would I start worrying about changing amps.