Tube rolling is fun. I have a couple of components which use 6 volt small signal tubes (6DJ8, 6922, 7308). The tricky part is getting good tubes. Unless you have access to a reliable tube tester you are at the mercy of the tube seller. A weak tube will still work for awhile, but you would never know it's weak without a tester. If you are serious about tubes, a tester is a must. You can pick an old surplus miltary tester (TV7, TV10, etc.) for a few hundred bucks. Electronic surplus stores are an excellent place to shop (or ebay) for a tester as well as surplus tubes.
How do you test different tubes?
I hear people recommending different brand of tubes for amps, preamps, etc. My question is how are people doing this? Are there dealers who loan tubes like other gear? I would hate to have to purchase different sets of tubes, try them, find the one I like best, and then trying to sell the set I don't like.