Here are the 3 options for Power Mode.
5. Power Mode Selection
The Power Mode switch has three settings – “Trigger”, “Auto”
and“On”. In the “Trigger” position, leave the Master Power switch
in the “On” position and set the Power Mode switch to the
“Trigger” position, then the amplifier will automatically turn itself
on and off when 5-30 volts DC is detected or removed from the
rear panel 1/8" Trigger jack. Tip is positive, ring is negative.
There is no delay when using the Trigger function. In the “Auto”
position, leave the Master Power switch in the “On” position and
set the Power Mode switch to the “Auto” position, then the
amplifier will automatically turn itself on and off when an audio
signal is detected or removed from the rear low or high level
inputs. There is a 2 second On delay and a 15 minute Off delay
when using the Auto Power function. In the “On” position, the
Master Power switch turns the amplifier on or off. Set the Master
Power switch to the “On” position and set the Power Mode
switch to the “On” position, then the amplifier will turn itself on
and off with the Master Power switch.