Power blackouts - problem for tube amp & speakers

With most tube amps its no worries at all.

I use Serge protection when confronted by churlish Italian waiters.

How about a electromagnetic cutoff on the ac that is supplying power to your stereo system; loss of power the electromagnetic drops out and the contacts open and they can not close until manually reset by a person.

I would see this as a bigger problem with a solid state amp, simply because when the power comes back on, it will be possible to thump on account of the preamp.

Most tube amplifiers should take a power outage in stride with no worries- I know ours do!

The controversy is over putting something between the wall and a power amplifier, which most manufacturers will say is detrimental to the amp's
performance (power limiting, extra noise on the line, etc.). I have solid state equipment that has a computer circuit that will ALSO put the components
in standby and have to be MANUALLY reset before i can play music again.
it is very annoying and if the circuit that must sniff the line 24/7 (even when the amps and preamps are not in use) should finally wear out, my precious stereo must be packed up and sent to a repair facility. And therefore, many dollars spent later, i get to listen to my system again.
OTOH, My central Air Cond. and refrigerator also draw a lot of power, but they will rarely break down under similar circumstances. Welcome to high-end audio...