The Coleman Audio M3PHMKIII has been upgraded with a 47 position stepped attenuator made exclusively for Coleman Audio. This is the most accurate level control available period. Perfect for mastering. Four stereo inputs to A/B input signals. Three stereo outputs for main and alternate speakers. Output #3 can be switched to a fixed output for meters or a cue system. Engineers headphone output has it's own level control. Left and right mute switches, a mono sum and a phase reverse switch. When the phase reverse and the mono sum both are engaged you get a L minus R in the speakers to monitor the side channels. The main signal path is passive, so no noise or coloration will be added to the audio signal.