I have a friend sending me his NightHawk in a few days and another friend will be bringing over his 1990 in mid March so I'll be able to compare them.
My friend who is coming over with the 1990 had the NightHawk but sold them since he though it was too dark so the etched treble is something I'll try to be aware of. I don't suspect it will bother me since I like my RS2e and modded SR-225e which are quite bright but so smooth.
Ah okay. Hope you enjoy the DT 1990. It was weird, but it really came to light after I spent more time with the Hawks and other headphones I noticed the treble. Problem is the treble etch distracts me from the dark sound signature. Similar issue I found on the Fostex woody phones. I'm still debating between the DT 1990 and Amiron. I am going to sell one of them.