tube equipment dates back way before protection circuits were required for SS. none
of the dozen or so tube amps I have ranging from 1960's Dynacos to today's amps
have anything close to even what a cheap SS amp has - like a fuse in the B+ lines.
it is not an issue with well maintained equipment - it is an issue with the design. about
20 years ago there was a rash of articles on adding simple fuses to the B+ line, through
the output transformer taps, through the center tap of the power supply transformer.
if you take a tube amp, maintain it to whatever it requires to prevent a power cycle
issue, then warm it up and power cycle it, often.
sooner or later something will go wrong.
this is less likely to happen on SS amps, even with those with a cheap/simple fuse
in the B+ and/or B- supply lines.
I have 3-5 tube amps and am NOT willing to power cycle them. there are folks who
buy power control units that time delay the re-power-on in case of a black or brown out
just to add time to allow cool-down, electrical drain down, etc.
this might simply be a statement from someone who doesn't have a tube power amp.
and however, if you have actual hands on experience with rapid power cycling of
a tube amp, then I'd like to hear which of all the tube amps this is, I might sell off ALL
my tube amps (4 PP el34 power amps, 2 SE integrateds, 2 tube-based headamps/DACs).
and buy this one-of-a-kind