Start with the content, not the knob
Write what each listener needs to hear. If the content differs, you need independent routing; separate volume controls on the same source are not enough.
Follow the outputs
Identify which hardware or software output carries each mix and whether those outputs can operate at the same time. Do not count a connector twice.
Keep unresolved routes visible
If the interface documentation does not establish the required independent path, keep the requirement pending rather than relabelling a shared mix.




