FWIW on Jet City's website, they sell a version of the JCA20H head that they call the Comet that (besides a new baffle) has Sovtek 12AX7s and matching JJ EL84s. The site says that they chose Sovteks for "high-gain, low-noise, and long life."

I wouldn't mind taming the noise a bit on my amp at volume but a) it's not a huge deal and b) between my fluorescent light, my CRT, and the fridge/freezer in the next room, my office is a noise factory. Someday I'll get JJs from Eurotubes, but we will see . . .