[superuser2]

>No it's not

I'm sorry, but you're wrong. I've worked in concert halls with half-million-dollar sound systems. You don't flip the power on upstream devices (DSPs, boards, etc.) while the amplifiers are powered on.

In nice, modern installs the system integrator will usually have installed a sequencer. You turn a key and what is essentially a glorified rackmount power strip emits a series of clicks as relays on a timer power on sections of the rack in a safe order. Otherwise it is up to the engineer to start up and shut down according to the correct procedure. A mistake will not necessarily damage equipment, but you will hear it pop - which may be anywhere from subtle to deafening. It is a dumb - and not unheard of - way to blow a speaker.

This is becoming less of an issue as digital audio networking (Dante, etc.) takes hold - there may be no analog connections between the mic itself and the amplifier - but it is absolutely standard with analog interconnections.