After a good session of side by side testing between the HD660S2, HD650, HD600, HD490 Pro, AKG 712 Pro and the Audio Technica R70XA the HD660S2 came out on top for my listening purposes (music wise - post rock instrumental - ie Mono, Explosions in the Sky, Godspeed You! Black Emporer etc etc).

I can imagine the 600/650 would be great from a vocal perspective and the 650 was a close second for me, but they didn't have the oomph and came across thin on the tracks that matter (mladic and nowhere, now here for example) . The 490 Pros were ... Weird ... Muddy but not. I can't quite figure it out still but the sound from them was way off what I like and were the first to be eliminated.

The R70XA's sound profile might have been there but the fit and the material quality out me off from the start and I couldn't get past that. The 712 Pros were a little similar but more an issue for the size of my ears.

Anyways, I'm already in love with these and the more I listen to, the more impressed I am.