Firing up old tube amps. Should I worry?

Buy a cheap pair of speakers from Best Buy, stand back, put some safety glasses on, flip the switch and use the return policy.

why Best Buy you can buy used car speakers from autowreck yard for $4 pair and connect them.

Marlin38,

How about pulling the signal and power tubes.

If the rectifier is a tube you will need to leave it in.

If you are worried about powering them directly off the mains put some kind of load in series with an amp first.

The wife's toaster or maybe an iron. Something with around 500 watts resistive load.

Fire it up, sorry couldn't resist, and check power supply dc output voltage. Leave it on for a minute or two.

If no smoke plug the amp directly into the wall recept.
Check power supply DC voltage.

If everything looks OK unplug amp install tubes.

A couple of cheap speakers might not be a bad idea for the ultimate test.
.

Find a repair shop with a variac or buy an inexpensive one. There is a good chance you will need it again in the future.

Don't say FIRE up
Alan