I had a similar issue with my setup (Mezzos). The Utopia tweeters can be a little unforgiving, but once I treated my room with ASC pcad panels, the glare/ringing went away.
Speaker glare...help
I have a small room 15-15'(yea I know but you do what you have to)..running a pair of Focal mini uptopias/rel storm3 powered w/ a pass labs X150.5 and jadis jpl..arcam 36...virtual dymanics cable....Im getting what appears to be a speaker glare in the 10-15 range or possibly distortion,I belive its not distortion..Ive tried numerous different speaker placements,seating postions,wall panels,different players,different tubes in jadis..anyone out there with ideas before I throw money to wind..thanks,D