Amps Always On - System Power Up Sequence

i've always been advised that it's important when powering up a system to 'follow the signal', that is to say, turn on the source component first, then preamp, then power amp, as this prevents pops that are potentially harmful to the speakers.

for those that leave their amps on all the time (class d seems to favor this), how does one go about safely powering up their system? is the 'follow the source' advice from an earlier time and perhaps is no longer necessary?