Pass Lab x2.5 preamp owners -- plse help

A week ago I purchased a 1 year old x2.5 to replace a adcom gfp-750. I notice more detail in the mids and highs, bass has improved but my system sounds more 'bright'. I'm using a Proceed HPA-2, Naim CD3.5 and flatcap. have @ 300 hrs on new acoustic zen satori speaker and Matrix Reference XLR between pre and amp. Signal Cable power cords except to CD player. Focus Audio FS688 speakers with empirical jumpers. Naim recommended I plug all of this into a wiremold power strip, which i've done. When I was using the adcom-the mids/highs seemed more etched but not as bright sounding. I would like to someday move up to a Pass Labs amp, but in the mean time would like a cheaper alternative. Would a different power cord tame some of the brightness. Or maybe there just isn't good synergy with the Proceed? Before buying the Pass I didn't read anything saying that brightness was part of its 'sonic signature'. Thank you for any and all advice.