[MrFixr55]

Varistors are useful on units with solid state rectifiers and high value caps to limit inrush current. Common to add these to such units like the Fisher 400, 500 and 800 series Hi-Fis from the late 1950s to early 1960s.

Only issue that I have with using a matching transformer as opposed to a standard audio output transformer is that the 70V matching transformers are not designed for a DC component. If you really try to use one, use a 70V primary. I don't think that you are gonna get the turns ratio and current capacity needed from a 25V Unit, but I defer to Ron Ramirez as he has actually done it.