Yeah, just flex the headband a little, that'll fix the clamping problem
On the topic of the DT531s, I don't think they sound technically better than the DT931s, but I find them to be far, far more enjoyable to listen to.
I never get sucked into the music with the DT931s, I find them a little distant and impersonal - sure they have a fantastic soundstage and clarity to die for, so they're great when you're listening to
the headphone but when listening to
music I much prefer the 531s.
When it's DT770 vs 531, I prefer the 531 unless I really need isolation, add an amp to the 531 and the bass reaches similar impact levels to the 770pro (which really need an amp to drive in the first place).
Other things I like about the dt531s;
price (low)
weight (low)
easy to drive without an amp
enjoyable overall presentation of music
I don't care if they're not technically better, or if "the high end is a little rolled off and there's a bit of a blahblah hump in the yadda range" Yes there are more expensive headphones that have a flatter, more accurate response, but they just don't have the love.
They sound
right
Forgiving, yet detailed. Warm, but not dark. Fun without sacrificing quality or fidelity.