Is my new amp TOO GOOD?

May I ask the question: Are you using any silver interconnect cables? Silver can add a brightness to the presentation from my experience.

What jumped out as a red flag for me is the speaker positioning. 
11 feet apart is a bit much. What happens when your speakers are spread so far apart is you don’t get the midbass and midrange filled in. I have experienced the exact issue you’re describing and in my system I solved it permanently by moving the speakers closer together. My recommendation would be to start at about 7 feet measured between center of woofers. Toe in so that they cross about a foot behind your head. Listen to it and start moving them apart keeping the same toe in. I’m pretty certain that with speakers set between 7-8 feet apart you will eliminate this problem. Set your listening position to be approximately 84% of the distance between speakers (woofers). 

When we upgrade we think it’s an auto improvement? No , you have to wait till the new components settle , Be patience. When the system settle , you can slowly analyze the sound .Op even if you only change one interconnect  the sound of your system change. With the addition of new amp , you got so many changes.So slowly figure it out to match the new amp in your system? Maybe burn in is all you need.

@mojo771  I don't have your gear nor have I listened to it, but after you try some of the other suggestions e.g. break-in time, speaker placement you still find the top end to fatiguing  maybe swap the 12ax7s for lower gain 5751s.  

90 db is too loud, you WILL regret it later.

I suspect something was not quite right before, and now you are hearing things that were always there in the content, but not in the playback.