Master Section of ToolMix8 - Analog Summing Gear ToolMix
The pictures shows two of the eight input channels of a ToolMix8 analog summing box and the master section with master fader, FDR-ON switch that inserts the master fader, and PFL to Output switch, that routs the PFL master automatically to the main stereo output, when a PFL switch is pressed.
analog Summing Box ToolMix8 

ToolMix8 detailed View Master Section