I'm sorry to be such a disppointing person to some of you
You’re not disappointing anyone here, and in fact we’re just trying to help. If you don’t agree with some of the suggestions being made that’s fine. The thing is, the KEFs aren’t dark sounding speakers so it’ll probably be a tough ask to find speakers that are bright enough to counteract what you feel is the amp’s sonic signature. Another way to go might be to try different cables — what speaker cables/interconnects/PCs are you using now? It’s possible that adding something like silver interconnects could inject some of the air/sparkle up top you’re currently missing. Just another idea FWIW, and best of luck in getting where you’re looking to go.