Hi, looks like as AKG also releases a new top of the line closed headphone - the K550 with 32 ohms / 1/4" gold jack .
It's listed in their new official 2011 catalogue, which can be downloaded here:
It is positioned above the K701, as you can see here in exerpts from the brochure:
i have no info about prices or release date, just stumbled about it by chance. looks interesting, though.