Just a heads up to those interested in the DT770/600 ohm because they heard it was well balanced. I recently got mine (just shipped them back), and they were anything but balanced. It appears that their latest version have added bass ports (near the yoke that connects to the cups). The bass ports apparently weren't in the DT770/600 before.
I definitely got the 600ohm.
In any case, with the bass ports now being in the 770s (at least on mine), it added a ridiculous amount of bass into the sound. It pretty much reminded me of the 770 Pro 80, but with a more present mid range. Still, the bass was near headache inducing.
Covering up these hole drastically reduced the bass to something even more bass light than the K701 I owned.
I'm guessing covering just part of the hole (not all of it) would leave a bit of the bass in, without sacrificing it entirely.
On another subject, I'm loving my 990/600 so much that I MIGHT get the 32ohm version in the future to use when I'm away from my desktop setup, and pair it with my E7 portable amp. I know it's not the exact same, but I doubt the sound will be significantly different.
Not getting it anytime soon, but something I'm considering.