I've got a recent Zu cable (bought it in November) and My HD600's have the Ribs/nubs on the inside of the connector socket. It's a tight fit, but it fits perfectly. No wiggling once it's in. You're not going to want to take these guy in and out alot for sure.
Then again, my Zu's are staying in my 600's for along time.
-Ed
Then again, my Zu's are staying in my 600's for along time.
-Ed