I think the DT770 Pro 80s would make a nice compliment to the HD598s. They still have a decent soundstage for closed headphone, and they're quite well balanced despite having boosted bass.
It's funny that they cost less than the M50s, despite being superior in every way.
"Problem" is, I've heard similar things about the M50x.
People say, the DT770 can get annoying after longer times because of the peaking Highs but the M50x seem to be less comfortable...
I can return the cans for 33days so maybe I'll order both and decide?
I'm still looking for more advice tho :3