When you are about to check the bias on a tubed amp with a hand held digital voltage meter Should the amp be off before inserting the leads of the meter or is it safe to insert the leads with the amp on and playing Thank you
I plug in my multimeter while the amp is on. It's safe. If your multimeter has a loose lead, however, you'll get a snap-crackle-pop through your speakers. That will definitely shake you up, but it won't hurt you.