Basically tubes are relatively noisy high impedance input devices. To obtain decent noise performance from a tube mic you need to raise the input signal as much as is feasible before feeding it to the grid of the first stage (which is where most of the noise is added).
Really helpful for a learner like me to understand that - thank you.
A 1:5 input transformer is relatively straightforward to make whilst retaining an excellent frequency response and contributing very little noise. With care a 1:10 transformer can be make with little compromise in frequency response and noise. With extreme care, and a lot of money, a 1:20 transformer can be made.
Is it possible to utilise a hybrid design, with a 1:5 input transformer coupled to a solid-state gain stage to bring the gain up to be comparable to a 1:10? I appreciate not an idea for the purist... just curiosity more than any intention.