Help with Speaker Selection

My room is 20x20 with a ceiling that slopes from 8 feet on the sides to 16 feet in the center. The system is ARC 150.2, Naim CD 3.5, Sugden pre-amp and speakers Linn Keilidh.

One side of the room has 8 foot high shelving upon which the speakers sit. So speaker placement remains less than ideal.

I play rock and roll mostly. Any part of the system can be replaced but I have always enjoyed the ARC sound.

Will entertain any suggestion.

Thanks to all for their comments.