Has anyone compared the EMT 139st phonostage to others ?

So if they’re in series, then the net voltage gain is a multiple of the individual voltage gain of each SUT? For example, a 1:10 ratio will increase gain 10X at the secondary of the first SUT. Then that voltage would be again increased by 10X across the second SUT, for a total V gain of 100X? Why would that ever be needed? I must misunderstand the hookup.

Wow! What a wealth of information from Good Music. I will never own an EMT anything (not because I don’t like the company but just due to my own old age and set preferences), but the historical perspective GM conveyed is very interesting. I am left with one question and one opinion.

Question: Why and how do you use two SUTs per channel?

Opinion: A 12AX7 or any tube that closely resembles the 12AX7 in its parameters (very high mu, very high plate resistance, very low current capacity) is a bad choice for a cathode follower. Because such a CF will have a relatively high output impedance and a low current carrying capacity, and it is after all the job of a CF to convert a voltage to current in the process of lowering output Z. In other words, the 12AX7 is not a good driver tube. I do realize it has been done by companies other than EMT, or the various persons that make their built in phono stages, and it may sound great.