Once you decide to stick with tube equipment, I advise keeping an eye out for a decent tube tester. Knowing their relative strength and testing for shorts, that is way beyond the world of darkness that you live within without any kind of testing ability.
I check all my tubes routinely twice a year, and have the benefit to check, know their status when I buy them new or used ones I find or friends give me; or whenever any issue pops up, like the imbalance I just traced to a poor connection of a cable that never gave me trouble before.
Today I am changing the connectors to these compact ones, see the video
Tight RCA Connectors, screws, no solder needed