Just to re-iterate what's been said from another Krell 300i owner. I would look at the cdplayer as your problem. I have an average cd player (Sony ES85 with an Audio Alchemy DITB) and sometimes experience what you describe. When I listen to the same CD recording on vinyl the brightness goes away. It happens mostly on your average rock recordings for me. That said, I have had the Levinson 39 and the Theta Miles hooked up to my Krell and the sound was glorious on every recording I tried. The Krell does take careful matching from the digital I think auditioning some good CD players will show that to you. Good luck.
It's not the sound I want!
My system consists of a Krell kav300i, Aeriel Acoustic 6s and AdcomGCD750. I have Cardas cables , Jenalabs interconnects and Synergistic Research ac chords. It sound great at times but I find many cds hard to listen to. I listen to vocals with acoustic guitar and the guitar sounds detailed but so metalic and unnatural. It sounds like sombody is playing a saw with a bow. Is this what digital really sounds like? Is it sytem matching? I dont think it is the speakers. Is it just a matter of settling for the best we can get for $8000.00 and limiting what we listen to?