I agree with Bemopti123. The bright problem started with the BAT amp, you could try band-aids like MIT cables and/or Shunyata power cords. However, I would recommend switching to a amp more suited to your tastes. Your speakers and preamp say that you prefer a warmer than neutral sound. You may want to try a Classe amp if solid state, or maybe even a tube amp.
Good luck,
John
Good luck,
John