The RA63b is an eight channel mono- or four channel stereo distribution amplifier designed for the contractor / install market. The outputs are designed to drive high-level balanced lines in a sound distribution system. The screw terminals on the rear panel are for input and output- and each output may power more than one line.Mono or Stereo Operation - mono input to eight outputs- or stereo inputs to four stereo outputs.+20 dB Gain switch.Screw Terminal inputs and outputs.The RA63b replaces the old RA63s. The new ra63b has all the same features- but has an easy access stereo mono switch.Specifications:Input Impedance: 100 K Ohms balanced.Max Input Level: +22 dBV.I/O Connectors: Screw terminal; + -- and ground.Output Impedance: 50 Ohms balanced.Max Output Level: +24 dB.Max Gain: 20 dB.S/N Ratio: >90 dB.Frequency Response: 10 Hz - 40 kHz- +/- 1 dB.THD: <.008%.Power: 120 VAC 50-60 Hz- 15VA.Size: 19- x 1.75- x 6.5- (48 x 4.5 x 17 cm).