Blasphemy! I want an 1/3 octave EQ

Here’s why... first my gear:  Goldenear refs, Klipsch 15 sub, M&K 12”V125, Roon Nucleus.  Oppo 103, Thorens TD165, Schiit Yggdrasil, Carver 275 amp, Prima Luna EVO preamp.  

I want to accomplish to primary objectives.  I want be able to tweak the speakers for my ears, not my wife or friends or employer, yep just for me...The acoustics in my room are pretty spot on, acousti mats in the right places and first reflections tamed.  All in all I think it’s a killer system.  So here’s the problem (notice here’s).  I’m 67 and was in sound reinforcement business in my youth.  Part owner of BP sound.    We were part of Kiss’s first tour.  We did stage and arena sound.   Tour with several bands for approx 5 years.  So I do have some hearing loss primary higher frequencies.  I want to eq the higher frequencies but I also want a balance control.  Neither amp or pre allow that.  So plz don’t try to talk me out of this, but please help with product selection.  I plan to place the EQ between amp and preamp...Thanks in advance for helping!!   And of course I don’t want to introduce noise or distortion, so Lpad solutions are out...