Those EF86 are from Cifté ...............Good tubes ..................also EF86 Telefunken and the Z729 GEC......... Philips group and Brimar..............
Crappy Russian copies GEC KT 66S will make the amp sound right.... And they last forever... Those Russian things r v unreliable as well as sounding like transistors... But what does it matter playing anti Establishment Taylor Swift or Die Straits