I don’t have any room treatments - But again, I don’t experience brightness or harshness as problematic on most recorded music.
You may be right that my amp is clipping when I have it turned up a bit so I’ll reconsider that. (Interestingly, I can listen to Beethoven (my favorite) symphonies and piano concertos at full volume without this effect(. But, Mahler does like massed everything and you could well be right that the organ tones underneath the high brass, with added triangle and crash symbols may be too much. Too much for my amp, too much for my ears.
I’m still going to explore the micro phonics potentially affecting my gear as that seems logical to me the more I think about it.
Kind regards to all - and thanks for the thoughtful replies.