Im tired and cant be bothered to write much but i will just say this. They have completely flat bass extension you wont find in any other headphone, great mids and no treble peaks. The sound signature changes slightly depending on what revision you try but if you want a hd 650 with greater bass extension and slightly more of everythign else then these are the phones for you.
I tried them 7 months ago, all i can really say is that they were "meh". Just didnt impress me, they werent bad but they just didnt sound great and i cant really remember specifics sincei t was a whiel ago.
Its a shame the railing take up so much of the frame 5-10.
Here are two of the few pictures ive stuck in my flickr this weekend.
IMG_1225-2 by Phil watson, on Flickr
IMG_1317 by Phil watson, on Flickr
Personally after moving from a 280x CF to a 980ti at 4k, the single card experience is much better. My 980ti overclocked is about 30-40% faster than my 280x CF and thats in gams that support crossfire never mind the games that dont.