It's an 802-VLZ3.
All inputs have MUTE ALT 3-4 selected. ALT 3-4 is selected for Control Room Source. Assign to Main Mix is selected. Ctl Room/Submix level is at the Unity detent. Main Out L/R send the final mix to the amplifier inputs. Headphones in Phones.
This keeps the headphones working independent of the Main Mix level setting.
Did I have to stare at page 26 of the manual for about an hour to figure this out? Well, yes. :-(