The Behringer Ultralink Pro is a combined audio splitter and mixer in a small rack-mounted unit. Every audio setup should have this, dubbed the audio version of the ‘Swiss Army Knife’.
The Ultralink can act as a distributor, sending a stereo input to several individually controllable outputs. Or, it can serve as a mixer combining several inputs into a single stereo output. Each channel can operate independently in each mode, with an easy to use push button mode switch.
We often use this as a distribution unit for large PA or audio systems, linking together multiple ‘zones’ of speakers for individual control.