I wanted to test it today to make sure......

Our global AV is one way. Select rooms then select a source that gets routed to them.

We have a single set of volume controls just like you and it adjusts the currently selected room or rooms.

Originally the programmer had some very cool features but the clients were having some trouble with it so we changed it slightly.

IMO the gloabal audio video page is the most important feature of the panel. The customers LOVE it.