Hi Marcus,
create a fadergroup which contains the fader of "Main Out" then you control all faders of this group with the ARC USB.
"Main Out" and "fader group" are on a per snapshot base.
So with 8 Snapshots, you can create plenty of different settings according to your demand.
If you need even more than 8 different snapshots / settings, then store the workspaces into Workspace Quick Select slots.
Then you can recall them easily with ALT-1 … ALT-0, then you have 10×8=80 different snapshots "at your fingertips" / recallable by such an easy key combination and next by selecting the desired snapshot with ARC USB.
When storing your workplace with the 8 snapshots to such a quick workspace select slot (30 are available in total),
when I would take care to store it with the snapshot being active that will most likely be used from those 8.
This saves you the time to change the snapshot by using mouse or ARC USB.
Workspace // Quick Select Slot 1..30
TM FX 1 ... 10 .............. 30
Snapshot ALT-1 ... ALT-0
1: 1* 1
2: 2 2
3: 3 3
4: 4 4
5: 5 5
6: 6 6
7: 7 7*
8: 8 8
So when pressing ALT-1 Snapshot 1 could be selected automatically, with ALT-0 Snapshot 7 might be activated automatically when saving into the workspace quick select slot with these snapshots active...
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14