Within your budget, get the Denon AH-D1001K cans and a Corda Headfive/Arietta/Swing amp from Meier Audio. This is without a doubt the least fatiguing setup I have ever heard. I have very sensitive hearing, especially to high frequencies, and this setup is comfortable for me to listen at high volume for hours on end. They are also the most comfortable to my head as well. The Sennheiser HD595 and HD650 on the other hand often give me a headache and cause ear pain. I mainly listen to classic rock, jazz, and some classical if that helps.
Don't be turned off by the Denon's modest price, they reveal just as much as the HD595's albeit with much finer grace and far tighter and silky smooth bass, and, most importantly do not scorch your ears. Neither are the most analytical cans in the world, but excessive detail causes my ears to hurt as well.
Other amps may behave differently, but with my Meier amps, Senns are often a very poor match.