I bought DT990 All Black, same pair with different name, on massdrop 1 year ago. I use for daily use, 10 hours day for game/music and films.
The sound stage of those headphone are amazing for me, very good and persistent bass and very clear treble. I try it first with Battlefield 1, the sound of a exploding shell seems all too true, that headphones excite me, the tones are not real, not neutral, they give a lot of color.
The problem, uncomfortable, a lot if used for more hours, previously i use hd518, another world for comfort.
Indeed 1 years later i order new PC37X, i think they will arrive in the next days.
I can confirm you that use headphones and a external microphone like massdrop modmic or similar is too uncomfortable, 2 wire and other problem.
Another problem, ok, for music and film they are perfect, but for gaming, na, they don't have a lot of spatiality, for most game is good but if u be a bit competitive u need to hear footsteps'sound very good. Sennheiser is known for neutral soundstage and lor of spatiality.
Ah, i have the 600 ohm version and i drive it with Darkvoice 336 Valve Amp, they need a lot of power for bring out their full potential and Tube amp are very good with this sounstage. I use them with my Oneplus 3t, but a very powerfull amp drive them in very different way. For 250 ohm is ok, the mb can drive it but if u want to use them very good, u need a separate and external dac/amp.