The Revelator io24 should have an option (maybe in Universal Control) to be powered off.
My PC has powered USB so the interface is always on even when I turn off the PC. The only way to power it off is to remove the usb cable or entirely shut down the power supply of the computer. Both unpractical options.
I don't know if this can be done via firmware update, but an option to manage the power state of the interface would be really great.