I just bought a used PS Audio preamp that came with three pairs of PSVANE 12au7 Art series tubes. One pair was in the preamp and the other two pair were still in their boxes. All of the tubes were noisy and within a few weeks, 5 out of the six tubes started making clicking noises. There is nothing I can see happening and there I can see wrong with the tubes, but I know that doesn’t mean much. Anyway, I bought a pair of Gold Lions and they have been working fine for almost four months now.