The Devil said:

Have you any experience with the Svetlana KT88s? They seem to have a
very shiny rep (some say they're as good as the original GECs).

I've only used the 6550 Svet in the past.
A very fine valve, you will note.

I once traded a matched quad KT88 Gold lions for I don't know what,
but boy did I regret that later!

--
Sander deWaal
"SOA of a KT88? Sufficient."