In addition to interconnects & power cabling, what about your AC power? I had excess brightness (& some grungies) which was resolved with power conditioning. Now have two Chang Lightspeeds (a 3200 & a 9900 Amp, per dealer's recommendation) which do not limit current transients, as some other systems do. Or go whole-hog & try the PS Audio.
Source of Brightness
I have rigning ears from the brightness in my system. Linn Genki, Meas Baron, Magnepan MMM (1.6s ordered). What is the source and solution? Robert Harley in TAS on SACD said that the CD brigthness/harshness wasn't there on the SACD and in the past the best CD players balance brightness with detail. Are high end makers walking a tight rope due to an inferior souce format?