Let me back up and state that I love the Beyerdynamic sound. I've owned the DT-880, DT-770, and the DT-990, all before the T1. I sold them and bought new Beyers more out of curiosity than dislike of any model for any reason. I could have kept any of the previous Beyers I've had, and I'd still be happy with the sound. With that in mind, I thought the bass on the T1 (1st gen) was a little light, and prefer the bass on the T70. I run my SA-CD player thought a Schiit Asgard amp, straight, no extra EQ. I like the T70 sound, and I'd like to try the DT-1990 for the same reasons as listed above - I just wonder if they would sound better, pretty much the same, or not as good to my ears. At no point would I expect to be disappointed.
I've also tried out the Sennheiser HD-650, and didn't like the sound at all. Same goes for a few other models that are quite popular here.