About the Volume : The volume use the rotary encoder to control the volume, Rotate Clockwise to increase volume, Anticlockwise to decrease. If the SA-60 work as a pure amplifier, just turn the volume to MAX. The SA-60 has the memory for the volume, and it will limit to a fixed value if the volume is too high when start up. About LED :The LED Up: RED Power OFFGREEN Power ONRED+GREEN Power ON + Loudness ON The LED Down: RED 3.5mm input Green RCA input About output :The SA-60 use the BTL connection way. So the "Speaker-" terminal cannot swap or connect to the amplifier housing. Technical Parameters Output Power: 55W + 55W