steffen is right on.
For example if you have up to 64 inputs for example connected to the CDM64 and you want to process them differently for FOH and monitors, you set channels 1-64 up to use local inputs 1-64 and you set channels 65-128 up to also use local inputs 1-64.
You can affect volume by changing the gain on either channel (FOH or monitor) without affecting the other channel. Each channel (FOH or monitor) will also have it’s own EQ, gates, compression etc that won’t affect the other channel.
You can then set up your surface anyway you want with regard to faders. Unless we are talking about a very small number of inputs, you are going to need to use more than one layer for FOH and more than one layer for monitors. But you have complete discretion on how you set this up.
You can even set the surface up to only show FOH faders or only monitor faders and then switch between the two as needed using a saved scene. To do this, set the surface up with whatever FOH layout you want/need. Then save that as a scene as “FOH surface” or something like that. Turn on the “scene safe filter” and block everything except the fader layout. Then reconfigure the surface to only show monitor faders. Save this as a new scene called “Monitor surface” or something like that. Again, turn on the “scene safe filter” and block everything except the fader layout. Now you can easily load whatever scene you need and control FOH or monitors. If you set the scene safe filter correctly, nothing will change except the fader layout being shown on the surface.
