Need to distribute a stereo speaker level signal to multiple listening zones? The Helios AS-SS4 4 Zone Speaker Selector is the solution. It features a manually activated impedance protection switch. Turn it on to prevent the impedance to your amplifier from dropping below 5 ohms, regardless of the number and impedance ratings of your speakers. Turn it off when its used as a part of a system incorporating impedance-matching volume controls, allowing you to get the most out of your amplifier. For in-wall installations, use CL-2 or CL-3 rated cable for compliance with local building codes. When connecting a speaker and amplifier, be sure to maintain the correct polarity between the amp, the speaker selector, the volume controls and the speakers.