Good review and I agree with your review. Because I've got a DT770 250 ohms running EHP-O2 amp.
Great SQ

Excellent review, thanks! You've got me wondering how this one would pair with my Valhalla...there are times when the closed back design would be helpful.

I am using these with my Asgard 2 and Little Dot 3 and they sound fantastic. The Val is technically higher quality so the sound should be even better. BTW, I found these at Sonic Sense in the 32 ohm version for $169.99 new, delivered. Ask for Garrett.

I own a pair of DT990s and at almost less than half the price of the 600s, I know what I would lean towards. That said, you may want to sign up for Deal News emails. They were running HD 600s for $250 last week through Adorama.

You might want to try the 880 as an open alternative to the 770.

Thanks for the feedback guys. I would love to get my hands on the 880 also, but a friend has the 990's so those I know I can get my hands on. Hopefully soon.

Great review, a nice comparison between the 600's and 770. I haven't had the chance to try a Beyer yet, I'm guessing these would be a great start! Closed phones for late night listening would be a good combo.
 
Looking forward to hearing about the 990's!

Great review, i own a pair with 250ohm and using kasoo YJ-01 tube amp and they are sound amazing . you guys can try with a tube amp combo as well ... 

Well done sounds spot on to how I felt. Now try some more expensive closed cans and the differences between open and closed and the recessed mids starts to really narrow down. For the price though and application the DT770 pro is a high value proposition for many and deserves its success