EDIT: Spend the day with the Crack and and the HD800's. Also bounced back and forth between the HDVA600 and the Crack w/Speedball. Crack out classes the HD600, there is more exposed through the Amp than the headphones know what to do with. The crack vs the hdva left me feeling the above statements are even more true. I feel like the Crack was on par with the lyr2 detail wise, but not the hdva. The signature was not flat but presented more flat with the HD800 and was much tighter throughout the frequency spectrum than it was the HD600. The organic vs mineral was also more apparent, especially when it came to percussion instruments. Imagine, if you would, a drumstick striking a drum head... a well mic'd drum reveals things you'd never hear across the room... the hdva gives you the experience of the mic... the Crack gives you the experience of being in the room.
I kinda felt the same comparing my HD800 with my HD600, i like the HD800 also because it sounds less veiled in my ears and perceived "more" (quantity wise) of good sound that was perceived as better (sound wise).