The Dayton Audio MA1240a features a Class-AB output circuit that delivers superior audiophile sound quality and stable performance. Each of your installation's zones can benefit from the MA1240a's clean audio reproduction and exceptional functionality. The MA1240a can be stacked with other audio components and includes removable ears for mounting in standard audio racks (2RU). Two common or BUS inputs feed audio signals from standard line-level audio sources to any or all channels. Each of the twelve channels has its own dedicated input and independent level adjustment to provide further flexibility. By simply flipping a single switch, two channels can be bridged to increase the total power output for that zone. This is helpful when extra power is needed in certain areas. The MA1240a's manual, automatic on/off, or triggered 12V input turn-on modes facilitate easy integration into automated systems. For quick and easy troubleshooting of the system, each pair of channels or zones has a bi-color LED to indicate its operational status. Specifications: ? Rated power output per channel: 40 watts into 8 ohms, 60 watts into 4 ohms (0.09% THD) ? Bridged output: 80 watts into 8 ohms (0.30% THD) ? Signal to noise ratio: 95 dB A-weighted ? Input impedance: 18K ohms ? Input sensitivity: 380 mV ? Frequency response: 5 Hz - 20 kHz ? Channel crosstalk: 80 dB ? Dimensions: 16.7" W x 4" H x 14.25" D (tabletop configuration) ? Power requirements: 115/230 VAC, 50/60 Hz ? Stand-by power rating: 115V, 0.264W ? Weight: 30 lbs.