As long as we are talking preamp tubes,I can tell you I like almost any NOS 12AX7 better than the current production Russian and Chinese crap.RCA,GE,Amperex,Tungsram,Sylvania are all very good.The Mullards and Telefunken are very good but seriously overpriced,and in my view more beneficial to the Hi-Fi guys.I havent gotten my hands on any of the RFT's that some people here have talked about,but they seem to like them.I have been buying NOS for years and I have a lot of good ones,but I did have to cull out a lot of bad ones over the years.Buying NOS tubes can be a crapshoot,but in my experience it has been worth it.I dont know what you are looking for,tonewise,but a great replacement for a slightly lower gain,smoother break-up is the 5751,GE being one of the better ones,but I have a lot of JAN 5751that are just as good.I have at least one 5751 in all but one of my amps,mostly the V1 position.The amp that doesnt have one has the lower gain 12AY7 in V1.
