Dclaz - you have had an answer to your questions already! Comapared to the AKG 701s the build of the Sennheisers feels and looks a little 'cheaper' - the plastic is gloss rather than matt on the speaker housing which accounts for some of that effect. Also I like the way the metal headband on the 701s looks. This is superficial, however. The comfort of the HD 650s on my head is just great. They fit me perfectly. My hat size is 7 1/4 btw, if that helps. I also like the way that the cans hug the ear, whereas the 701s loll about a bit, the weight all being borne (painfully) by the top of the head.
Thanks, hat size is probably a good indicator. I should try and found out mine :)