The easiest way and best is truly in the equipment it will be used in.Tubes are sensitive to the circuits utilized is why I say this. However Hickok testers have a headset plug in to test also for microphonis but headsets are expensive and the tester is also. The best one using a tester was built by new york audio labs I think or the guy from the otl fame, but hardly ever comes up for sale, I have seen 2 sell in my lifetime.
