Are silver cables best for my system????

I realize you did not ask about speakers, but I had the same PSB's once and I could never get them to sound anything but cool (some would say neutral), and that was with McIntosh electronics...going the other way with anything but 'warm' components/cables I would think would keep them in the 'cool' or even harsh range.

Some basic and obvious things you may or may not have done.
1. Speaker placement: move them around especially distance from the back wall, some positions will increase bass thereby changing the voicing of your system.
2. Room treatment - Lots of hard surfaces, glass, hardwood floors, etc? Try some wall hangings, drapes or dedicated audio absorbent panels.

Although KCAG is a pretty good cable they are what, a 8 year old design. I found wire world gold reference to be less harsh - not really warmer just less emphasis on that upper mid, lower tweet range that emphasizes hard and bright. The WW are not cheap.

I am not personally familiar with the Adcom 750 but I'm guessing it's somewhat outclassed by the rest of your system.

Can you borrow equipment from fellow audiphiles to identify the "culprit"?

it all depends on the cables. good silver cables are anything but bright.

Herman. No I cant borrow. I am out in the country here. I am reburning them in some more. maybe normal playing is not enough. Mike

Maybe it's time to look at a speaker without the metal dome tweeter...just a guess. I've always found them to be a little annoying.Some tweets actually add more than what's really there. Sounds like you need a warmer speaker with some upper frequency speed.The last time I audition the PSB Golds I could hear the tweeters ringing or calling attention to themselves.

good luck