Hi, my first post here! I have just got a TLA 5051, and after replacing cheap Chinese 12ax7's (ecc83) for electro harmonix (Russian) ones, I am curious to know whether I can replace with ecc88's, as I hear these are nicer, and i have some amperex ones from holland, but do they have a different grounding pin config, and will this be bad for the 5051? The reason I ask, is although I have read up a lot recently about the difference between the valves, when I changed the valve (ecc83) from my Rode K2, to the advised, 6922 (ecc88) there wasn't a problem.. Yet there seems to be an advisory against using ecc88's instead of ecc83's .. Many thanks, for any light shed upon this.