there was a period when a lot of digital modules took power from the 5v, but the trend now is to convert +12v to whatever is needed by the mcu (usually 5v or 3.3v)

these modules were often quite power hungry too

most modules use comparatively little -12v (except video, argh)

if your psu has a lot of spare 5v and you have some space in the rack you could consider a usb power module (there are a few available) and charge your phone, power a led lamp etc

"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia

Utility modules are the dull polish that makes the shiny modules actually shine!!!

sound sources < sound modifiers < modulation sources < utilities