Multiroom

This is a audio system which can control multiple rooms or zones. There are also systems where you can listen to a different source in each zone. This is called a multiroom-multisource system.

This is a simple solution to control the volume of multiple zones. In fact, this is a zone controller. You can connect this device to your existing amplifier and control 4 or 6 zones individually, turn zones on and off and control the volume.