I had a similar problem with a pair of custom speakers using Eton metal dome mids and tweeters. The detail was fantastic but too many cd's had that upper midrange glare you're referring to. I would probably have just sold the speakers but they were way too big to ship so I tried several amps, tubes to hybrids to solid state, numerous interconnects and even more power cords. It was always a balancing act that eventually frustrated me. I began to experiment with various wire and AC plugs and found a power cord that tames that upper midrange glare but is a higer rez and not soft sounding cord. I purchased a 10 M run of the Mundorf 1mm solid core silver/gold wire (found on Ebay out of Taiwan), some teflon tubing, and a pair of the Iego 8095 rhodium over silver AC plugs (see acoustic-fun.com to acquire these). I cut the wire into 8 1M runs, ran 4 wires per pole and just used some cheapo radio shack lamp cord as the ground and WOW! The detail and air was still there, the soundstage was expansive with good image outlines, but the glare was gone, really gone. Using 2 of these cords made things even smoother but I felt that the image outlines weren't as sharp as I like but YMMV. Anyway, you're looking at about a $400 investment for a single cord but it most likely will cure your glare problem and not compromise your system. Good luck!
