Protection circuitry provides safety and reliability under heavy use. Amplifies up to four stereo line-level sources. Zones have dedicated line level inputs or can share a source via the bus input. Separate gain controls for each zone to present room sound levels. Zone output can be switched to stereo or bridge mono output. In bridged mode, a zone's left and right channels are combined for a higher-power mono output, ideal for large rooms or outdoor listening areas. A+B speaker output in 4 ohm mode. 50 watts per channel RMS @ 8 ohms x 8.