I have the following tubes to chose:
6SN7GT Brimar UK NOS. Red logo. Clear glass 170 GBP
6SN7GT Brimar UK NOS. KB/FE version. Black glass. 400 GBP
6SN7GT / VT231 USA NOS, Kenrad 160 GBP.
6SN7GT USA VT231. NOS, Tung-Sol, L round anode 300 GBP
6SN7W Sylvania USA NOS. Metal base 180 GBP...
Are also not so cheap :D
I still have to read a little about the different variants of 6SN7. The most expensive are GEC METAL BASE and BRIMAR "Black Beauty" cost up to £ 1000 per piece.
Abbas told me already in September that he ordered thicker cases. He wrote me in December that the thicker cases have arrived. It is very likely that these cases are already used.
I asked Abbas about details of the new case and whether it affects only my Signature, or other models. He answered that - there are double wide bridges on the sides, double bottom under the transformers 2mm instead of 1mm, such a case will now be for all 3.2s.
Abbas writes that he still gets electricity from the diesel generator and that fuel is very expensive at the moment. He tries to be in the workroom as much as possible to build our DACs and tries not to waste time on the computer.
He wanted to answer my other questions later.