TK16
Headphoneus Supremus
Check out this 7L0 Endy E88CC, first 1 I seen for sale. Very early 56.
https://www.ebay.com/itm/1x-e88cc-C...6c0aad379233567ffe94ad1|iid:1&redirect=mobile
https://www.ebay.com/itm/1x-e88cc-C...6c0aad379233567ffe94ad1|iid:1&redirect=mobile