I got one of these - works great to sequence-on (and off) preamp, fans, peripherals - and finally the amps are plugged into outlets 7&8 which get switched on last, individually - after a short 5 seconds or so delay between each. During shutdown the amps are switched off first - individually and with a 10 second delay between each, and then the other outlets are switched off sequentially.
No thumps, pops, or flying woofers, plus I can use an app on the phone to monitor power quality, remote turn on/off and usage per outlet...if I really had a need to do that. It also provides power filtration and voltage threshold monitoring.
https://www.panamax.com/product/bluebolt-controllable-power-conditioner-8-outlets/