Purchase tubes from a reliable seller it will be cheaper and the tubes will be just fine. Personally I'd go for NOS or good older pulls over current production 6922s. JAN/Phillips 6922's are typically a solid value. AI preamps have a ton of gain so they can really magnify a noisy tube make sure you get whatever you buy tested for noise.
Audible Illusions Modulus 3A noise
I purchased the AI M3A, love the sound, do not like the high noise floor - much more noise on one side now after only 10 hours or so of use. Reading through forums I suspect the electro-harmonics tube. Is a louder than normal static noise coming through speakers normally a tube issue?
Thanks for your help!
Kevin