there are power strips available that have master-slave outputs, and the slave outputs only become active when whatever is plugged into the master outlet is turned on. My son just bought a couple of them for exactly the same reason as yours, Rachel. He has music equipment that he uses at the same time, and only one of the items has an ON switch that is conveniently located. So he plugged that device into the MASTER outlet, and all the other stuff into the SLAVE outlets.

He keeps the switches turned on all the time for the slave devices, so they can be active when their outlets are active. Then, by turning on only the master device, everything comes on and stays on until the master device is turned off.

For equipment that is all used at the same time, and is located close enough to share the same power strip, it's a pretty neat solution.

They cost about $20-$30. I'll ask where he bought it and post that info later

https://www.dropbox.com/sh/ey71h8ep047758h/AAC12jNM0Hz9Q8zsh5iDeqNHa?dl=0