What are some good tubes to use in a Thor phono

stage? I was recently Spring-cleaning some of my components and took the chrome anti-RF cover off without realizing that I had not muted the pre. Normally, this would be no big thing, but one of the output tubes became Very Upset as I approached its little crown with my fingertip. Starting at about 1 foot away, that channel started to roar!

These tubes are the original factory chosen: a pair of Gold Dragon 12AT7 and a .5db-matched quad of Sovtek 12AX7s. While it still sounds good at all sane listening levels, and the trick reversed itself when I swapped the output tubes, I believe the fault is in the tubes and that the preamp is sound, but I have not shopped for tubes personally in my life. I always had a dealer I trusted to make decisions like what tubes to buy, but I have not found any I can trust since Salon I Audio in Wisconsin closed. My biggest concern is about the integrity of the 12AX7 quad's verification. They will have to be matched as closely as possible. Does anyone out there know a tube supplier that can be trusted to honestly put together a high quality, closely-matched set? I do not have access to tube testing hardware and so must trust a vendor for this critical purchase. Also, can anyone recommend other better tubes to go with? These originals were not very expensive at the time they were new (1999), and only cost $150 from the factory for a replacement set.