You don't have too much power. If anything, the problem is more likely get worse if you downgrade. Are you sure its broken in?
New Rotel RA-1570 seems to display the highs
I'm not sure if this is the way amp seems to play music. It just seems the highs are very pronounced, a little too much in my opinion. IT's a great amp in way that I hear parts of music I never new existed. I'm not sure if I have too much "amp" and maybe I could with the model below.