Welcome to HeadPhiles RexAeterna and thanks for sharing! (better late than never, I often say. hehe.)

Sadly, the only non-current production AKG I've laid my ears on are the K1k's, however, I don't think they've yet to be considered as true vintages relative to AKG's phone production history. Good thing that our Master Sensei Ken recently hoarded a good number of vintage AKG's from eBay and is anxiously awaiting for their arrival. And not until I get a chance to listen to Ken's incoming aural gems can they un-become audio enigmas to these ole' ears of mine.