It's tough enough for us to find systems that fulfill our wants/needs without trying to find equipment that "repairs" auditory limitations. You mentioned that a perçussive source such as a piano bothers you. I wonder if that is the case with live piano music? If not, then obviously your responding (bothered by) your present audio setup. But you've probably already made that distinction -- performed the is it live vs recording reproduction test.
I'm in agreement that your sources are less than reference level. Since its inception the silver disc has presented brightness issues that are nicely ameliorated by some of the better, more current digital sources.
With that said, I run stats in both my H/T system and in my 2-channel audio room -- Martin Logan's & Aragon 5-channel ss amplification in the former and Soundlabs & CAT tube amplification in the latter. Of course each room sounds different, but neither has objectionable frequency ranges.
My suggestion is to be very careful trying to correct objectionable frequencies with a specific design/type (e.g. tube) equipment. In your shoes, I suppose I would try to find a system at a friend's, dealer's, audio show that doesn't bother you to make sure that the problem isn't an organic one. And if not, try new sources and amplification (perhaps even speakers) until you find a combination that you can live with.
At any rate, good luck.....