Audio Research - should I replace the valves?

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No sweat, @cey .

anyway, the last time I bought output tubes was a couple of years ago; I bought a dozen of the reissued Tungsol EL34s from Jim McShane to replace a dozen of the reissued Mullards that I bought from Uncle Kevin that didn’t last very long.

I am a big fan of Jim McShane now. "

@immatthewj holy smoke i heard about new production longetivity issues, but man that sucks. i gotta say ive had no such problems, but i hear aout em plenty. been runnin new production tubes not-so-gently in my guitar amps for a long time with very few surprises, tho i think thats in the power section. funny i never paid no mind to tube selection til i started getting into hifi. always told my tech, hey, whatever makes it sound good. and it always sounded good.

also, both jim and kevin are known for testing the heck outta them. andy, i think, puts em thru the ringer as well, tho he doesnt do new production.  

@cey  , well, it took Jim a lot longer to get a batch of 12 together than it did Uncle Kevin, and once Jim took payment he would email me ever so often to let me know what stage he was in in the process of burning them in & testing.  Which is not to say that Uncle Kevin didn't have hordes of tubes burned in & tested with their numbers already established to choose from.  And, I did run those reissues from Uncle Kevin a lot harder than I run the tubes I bought from Jim (just the mood swing period I was in & presently am in). 

OP. As you are in the UK, Watford Valves have a good stock of 6550s for your power amp.

It looks like Tubeamp doctor in Germany has 6H30s - for your pre and driver valves in your power amps.

The latter are not massively common and are Russian, so harder to come by and likely to get even harder to come by over time.

@immatthewj  i hear u brother!