A big knob for monitor control - it's not cheap, but it is nicely made and does exactly what it says it should. For controlling your monitors when no dedicated volume control is to hand.
Behringer X-32 digital mixing desk, after our overview, I've attempted to answer all your questions - thanks for posting them. sorry if they were not all answered, but I will continue to post to the comments, and may be able to get another video done if I can get hold of the S16 and P16...