Hello thanks for your ideas. I like the way the 940 presents the treble - very detailed and organic-ish, but a little too harsh. So I've been playing around with trying some tubes in my amp that are somewhat rolled off in the highs.
I will search this thread for that headband mod - I just hope it doesn't break the wires to swap that out.
I actually already have the DT 150 from Beyerdynamic. While I'm not sure if it's a fluke of manufacturing inconsistency, my particular pair seems to have a medium/small soundstage. Yes it's very rolled off in the highs as you say. And a lot of other owners of it say that it's nor impactful enough in the dynamics.
The 940's have basically 0 soundstage though, so I think they are better suited for mastering, like in a studio for critical listening.