A total of 18 devices (sources or sub-systems) may be controlled by the Adagio platform. Pre-programmed audio sources are included in this count. For example, if you have two tuners and two iPods, then you can use the remaining 14 devices for other AV sources or sub-systems. Any open devices can be either sources or sub-systems in no necessary order. In addition, room sources if they are local to a single room and not shared around the system can all count as a single source. For example if four rooms have DVD players in them that are not shared with the rest of the house, then all four DVD players can be grouped into one device called "Room DVD" or something similar.