This is a utility module we found ourselves always needing and using. The four well spaced knobs can act as active attenuators or attenuverters (bipolar) depending on the setting of the two-position switches. Each input is normalled to a precision 5V DC voltage. With nothing plugged into the jacks, each knob controls a voltage amount of 0 to +5 v or -5 to +5 v depending on the position of the mode switch. 2 modes for each channel5 v normalled to each inputwith external signals it acts as active/buffered attenuator/attenuverter/mixerEach output normalled to mix into the adjacent channel on the right making it possible to do sub mixes in groups of 2, 3 or all four channels.