For even greater control of your distributed audio, particularly for larger systems, consider purchasing a dual source speaker selector. Dual source selectors switch your speaker outputs from two different (A and B) amplifiers/receivers to multiple zones. This means you can choose two music sources for each zone. For instance, you can listen to Spotify or your favorite radio station in any zone then toggle between them with the A and B switches. Dual source speaker selectors can control as little as four zones or as high as 12 zones and include features like impedance protection that helps amplifiers safely drive power to all those speakers and zones.