Haha I'm still considering the T1 (gen 1), I can't seem to find a direct comparison between it and the dt1990
I would choose the DT1990 over the T1-v1 hands down. To my ears, that v1 was overly bright and fatiguing. The 1990 is much more balanced and only sounds bright on electronics that sound too bright. (The Amirons are less bright still, but I prefer the 1990.)