I'll ask Phillip next time I see him and get back to you. I could be wrong, this is just what AKG's global product manager told me when we were designing the K7XX.
EDIT: accidentally a word
I don't think it's super important (now that I've already made a fuss) but i had two pairs hand in hand. The earlier production had a flatter pad and they sounded a bit different as a result. I figure the pad production changed at some point but they didnt change the part numbers.
You'd never be able to tell the difference without them side by side though.