Quick take of the left channel only, FR + THD.

Subjectively, these are very bassy. That's the first thought that comes to mind. Not necessarily in a bad way...it's actually pretty fun and doesn't sound quite as messy as the measured distortion might make you think. Very thick, very powerful, but not always in the horribly bloated and bloomy way you'd expect (not to say it isn't those things, just less so than you'd think from measurements). Midrange is good. Treble overall has a distinctly sharp and bright characteristic. That spot around 5KHz wore on me with longer listening sessions but generally isn't too bad because of the extra bass. U-shaped sound sig.

These also sounded faster and more detailed than I expected. I'm not sure how much of that was just false detail, though, due to the treble spikes. Soundstage and air were pretty good, perhaps a bit less left/right than the HD600 or 650.

If you haven't listened to anything else in a while, these are pretty fun and engaging right away. If you go to these after listening to something more neutral, they're pretty jarring for a while.

Might be a good candidates for mods. They look nice, they're comfortable, they run well from portable sources, and I think they have enough inherent potential that you could make them well worth the price tag with mods.