M-AUDIO EQMan - Manual (Page 4)

4
“Aux In” Jack
The “Aux In” is an auxiliary input which bypasses the equalizer stage of
the board. Its line-level stereo signal feeds directly into the EQMan’s
stereo volume control circuitry, where it is mixed with the Main In
signal that exits the equalizer stage. Because the Aux In audio signals
bypass the equalizer stage of the board, they are not affected by the
equalizer settings of EQMan.
“Main Out” Jack
Main Out is a line-level stereo output that may be connected to any
device that can accept a line-level stereo signal, such as a sound card line
input, an input on your mixer, or your tape deck. The audio signal at
the Main Out is sum of the equalizer section output (which Main In
passes through) and the Aux In signal.
Fig. 0 here
EQMan Block Diagram