That has alot to do with your personal taste, in the sound of the different tubes.
Probably the one that gets the most attention is the RCA Cunningham 45. It is a real nice tube.
Everyone that I have talked to prefers the new Emission Labs 45s over all of the older 45s. It is a personal preference between the EML solid plates and the EML mesh plates. The solid plates have more of the similar character to the older tubes, due to the similar construction with solid plates. The mesh plates tend to be more transparent, and a little more forward, but smoother at the same time. I have a pair of EML mesh plate 45s in my amp, and I think they sound great. Also, they come perfectly matched from the factory with the charts accompanying them. They also are warranteed. You will have a hard time getting a matched pair of older 45s from anywhere, and they certainly won't be guaranteed. By the time you go through several sets of NOS 45s, which might not take long considering the age and amount of time they have left on them, you could have a brand new set of matched tubes that most 45 freaks like better than the NOS anyway. Even if you get some that are about 85%, they are going to cost you at least $150/pr, and likely won't be well matched. My tubes came with a trace chart that showed the tubes were so well matched, you could barely see that there were 2 traces on the chart. Everything was perfectly over-scribed. I'd seriously think about the EML 45s. I went through the same decision process when I got my amp. I decided I wanted good matched tubes, that wouldn't poop out on me in a couple of months. I know that $425 is alot of money, but to me it was worth it.
Probably the one that gets the most attention is the RCA Cunningham 45. It is a real nice tube.
Everyone that I have talked to prefers the new Emission Labs 45s over all of the older 45s. It is a personal preference between the EML solid plates and the EML mesh plates. The solid plates have more of the similar character to the older tubes, due to the similar construction with solid plates. The mesh plates tend to be more transparent, and a little more forward, but smoother at the same time. I have a pair of EML mesh plate 45s in my amp, and I think they sound great. Also, they come perfectly matched from the factory with the charts accompanying them. They also are warranteed. You will have a hard time getting a matched pair of older 45s from anywhere, and they certainly won't be guaranteed. By the time you go through several sets of NOS 45s, which might not take long considering the age and amount of time they have left on them, you could have a brand new set of matched tubes that most 45 freaks like better than the NOS anyway. Even if you get some that are about 85%, they are going to cost you at least $150/pr, and likely won't be well matched. My tubes came with a trace chart that showed the tubes were so well matched, you could barely see that there were 2 traces on the chart. Everything was perfectly over-scribed. I'd seriously think about the EML 45s. I went through the same decision process when I got my amp. I decided I wanted good matched tubes, that wouldn't poop out on me in a couple of months. I know that $425 is alot of money, but to me it was worth it.