I've got a 1970 Twin Reverb chassis that I've been running with two TAD 6L6 output tubes in order to reduce the power. I'm happy with it as is, but have considered adding the second pair of 6L6's in order to sell it. One of the second pair is faulty, so I removed the two inside tubes as a quick fix and ended up liking it that way, but if I sell it, I'd want to make it right. Can I buy a single TAD 6L6 to replace the faulty one without worrying about matching it? I know that years ago, we used to replace tubes without matching them and they seemed to work fine.