In a nutshell, this is what you get when you industrialize a Grado RS-1, but improve the frequency response. No sizzle. No shouty, No massive-midbass. No shoutiness - maybe a bit nasal. Bass extends down low with better quality than any Grado and even the HD6** series. Overall tonal signature is mid-centric with easygoing highs, but not as laid back as the Audezes. Fast, responsive, and lively sounding. Resolving enough to scale with better gear. Sounds great with tubes.
Good description Marvey, the best I've seen in a while.
With a little bass EQ-ing (= up!), the bass response becomes very good as well, good slam with no bleed on the mids.
I would just add that you shouldn't expect a very broad soudstage, these feel lively because of the nice detailed mids and the medium soundstage.
Very serious cans, and the build is very sturdy.
And I'll add that if you're a real basshead (like I am), they absolutely will respond to whatever EQing you do and give you as much bass as you could possibly want.