The SS-4.2 allows you to switch up to four speaker pairs connected to a stereo amplifier. Offering high-quality audio performance, it also provides overload protection and long-term reliability. The SS-4.2 offers two operating configurations: Impedance Matching and Bypass. Impedance-matching mode provides automatic overload protection for use even with high-power amplifiers. This mode allows multiple pairs of speakers to be safely connected to an amplifier using the built-in automatic impedance-matching circuitry. Bypass mode is used for direct speaker switching with remote impedance-matching volume controls. This allows local control in each room as well as higher efficiency; however, in this mode the impedance matching and overload protection are not engaged. Designed for use with 8-ohm loudspeakers, the SS-4.2 also provides safe connection to bridged amplifiers and even works in applications where there is a floating ground. It has spring-loaded speaker terminals for quick connection and can accommodate speaker wire up to 12 gauge.