The McLELLAND Pro series stereo amplifier represent the state of art design. Featuring dual inputs with signal sensing, McLELLAND Pro series amplifier can be configured to turn on automatically when music is sensing on the inputs. The Input 1 will override Input 2 whenever the signal is present, this makes the Pro series the perfect amplifiers as a zone amplifier for multi room distribution system. Any time a local source is activated, it will take priority over the whole house audio by simply showing signal present at Input 1. Also, McLELLAND Pro Series Amplifiers have two pairs of speaker output to allow the amp to run a “ A” pair of speakers as well as an auxiliary “ B” pair of speakers and allows selection of either or both from the front panel of the amplifier. Moreover, the McLELLAND Pro Series Amplifiers can be switched on by the DC 12V trigger, which gives you the flexible -on options (only for Pro 200 & Pro 300).