I already published a post here about a clone of these Playback 60 headphones: https://www.head-fi.org/threads/vintage-playback-60.938678/ For half a year I hiccuped information about them on the Internet! And I found it! In this article on the 1975 Tokyo World Headphone Festival...

After all, the company Koss during the leadership of its founder John Koss was truly great, and then the optimizers came and it turned out what happened. Otherwise, how to explain the fact that the company could produce small-scale batches of headphones for "human testing". The case in the...

I bought it on Ebay for $ 24. This is a clone of Rystl Electro-3000 & Alarik CIS-3000 and Yes they are electrostatic (electret). I can tell one thing from the sound: it's very soft! This is the first time I've seen this..