No, there is a closed, modern, PRO4 with Titanium drivers. To the Koss-mobile!
From the Koss-mobile:
It appears that the closed model is "PRO4AAT" and the open model is "PRO4AAAT" - like I said, too many A's to keep it all straight. So it would be the "AAT" that is a pass.
The original 4AA wasn't very good either, so that's to be expected.