Hi
IMHO comparing headphones really comes down to two aspects, comfort and transparency.
The amp has as much to do with the second aspect as the headphones themselves.
I have Audeze lcd 2 with the sex 2.1 amp at 32 ohms and I believe that they are the best headphones on the planet, I did not feel that way with a different amp, that being said they are very heavy and I need to find just the right position to accommodate the weight, but then it is a out of body experience. I also had Senn hd and did not really like the fit and thought the sound was a little shouty.
I also have AKG Q702 and they are the most comfortable but very clinical in sound, on the cheaper scale I have Meze 99 Classics which are real toe tappers and Sony Studio MDR V600, and enjoy those as well. However when I listen for total relaxation late at night I always go to the LCD 2
They are heavy and I must allow for head bracing in the chair but once that position is found then I listen for hours on end. I have never listened to the HD 650, or the others that you listed, sorry.