Shrill high frequencies


I recently added an Isotek power conditioner to my system. Everything improved with one quibble; the highest frequencies are a bit bright for my taste. I'd be grateful if someone could suggest a workaround that doesn't entail replacing any components. Perhaps cables? 

ott

Did you allow enough ‘break-in’ hours? Also, experiment with PC feeding the IsoTek. 

Amp is Luxman MQ-88UC, preamp Audible Illusions Modulus 3b factory upgraded, sources Modwright modified Sony HAP Z1ES,.Magnum Dynalab MB 108 tuner. All IC cables are Cardas Clear , Speaker cables Nordost Frey 2. Speakers are KEF LS 50 or Goldenear Triton 1, subs REL Stentors.