I had a similar brightness issue with my Focal Kanta 2 speakers, which are my anchors for both stereo and home theatre. I tried the Schitt Loki Max, it was not a good all-around solution (had to fiddle with each track), sold it. I had a BHK preamp, played with different tubes and that had a positive effect when the right tube was used. Toe in, toe out, straight ahead, all made a difference until I found the best angle (straight ahead). The key was cabling. Cardas Cygnus was warm, their Clear works very well for me also. The last pair of cables I swapped in the system, Acoustic Zen Absolute Copper, made it for me. I feared I would live with compromised sound forever but the combination of cables made an amazing transformation. Good luck in your journey.
Robert