I was looking over the measurements for these on Innerfidelity, and they look like they have a lot of potential. They have a flat response down to at least 50Hz before they roll off, though this might not be an entirely accurate measurement due to the reports of these having quite a bit of bass. THD is fairly low. The 300Hz square wave is actually pretty good looking. Pretty clean looking with a bit of overshoot at the beginning. If I remember correctly, Tyll said that's generally positive.
They have a rather large dip between 2-7KHz and a peak around 7-10KHz, which I'm hoping I can improve with mods. I'm actually really excited to try these out!
What's strange, though, is how similarly these measured compared to my open-back modded D2000s (which ended up being an extremely ghetto mod due to changes I should have made, haha). Check out the FR response:
The top end is where the main differences lie, but other than that...interesting.