• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Step up interstage transformer

I've seen it mentioned it is a generally a bad idea to use them, it has to do with capacitance I presume.

Is it a good idea to use them as input devices? Say a solid state source driving an input tube?

Or use it on the output of a solid state amplifier (plenty of current, but not enough voltage gain) to drive a power tube?