My mixer has these Aux
Here you’ll find knobs that control the levels of aux sends A and
B. AUX A is either pre-fader or post-fader, depending on the
position of the PRE / POST switch. When the switch is in the
raised position, the aux send is pre-fader. When the switch is
depressed, the aux send is post-fader.
What does all this mean? In POST mode the aux send is affected
by the fader, EQ and HPF settings. In PRE mode the aux send is
affected only by the EQ and HPF settings. POST mode is
generally used for sending the signal to an external effects device
(so that the fader controls the signal level), and PRE mode is
usually used for cue sends (for example, sending a signal to
headphones while recording, for which you may not want the fader
to alter the channel’s level).
AUX B is always post-fader