Interesting stuff
http://personal.audioquest.com/nighthawk-measurements
Yeah man, incredibly interesting stuff even if you don't care about the Nighthawk at all. Huge props to AudioQuest for putting together such a comprehensive website explaining how they arrived at the Nighthawk. Does it mean you'll like them? Nope, but it does explain everything about them.
I have a loaner set right now that is almost fully burned in. They are very smooth and cause absolutely no fatigue. I enjoy listening to some genres tremendously on them (classical and jazz in particular). They aren't as fun as my Fostex TH600s, but I can wear them forever. Would I buy them at $600? Tough call. I'd definitely buy them at $400, but I'm still forming impressions of them and I don't know if I'd go full retail on them just yet.