Time for the Pro Jr to get new tubes. The old ones were Sovtek and held up well, but the amp is starting get dirty pretty quick. Seems I went through several pairs before finding some good ones last time. I've got a quartet of Fender/Groove Tube/Sovtek in parts drawer and tried them out~ 2 are way microphonic. Tried the other 2 and one makes a sound like clinking glass on warm up and shut down, doesn't make me feel very confident. Are there any real differences in reliability with current production EL84's? Seems Sovtek or Chinese are the available choices with various rebranding. Any consensus toughest EL84 available?