Connect the input of the in-ear monitor system or headphone amplifier to an auxiliary output from the mixer, or to a pair of outputs if stereo is desired for the performers using in-ear monitoring. Connect the wedge monitors to a separate auxiliary output.
Connect the Y-adapter between the auxiliary output and the inputs of both the monitor amplifier and the in-ear setup, if only a single auxiliary is available for monitor use. Because of the differences between them, it is preferable to run in-ears on a separate auxiliary mix.
Adjust the level of each mixer channel by using the corresponding auxiliary level control. If you are using a stereo setup, use equal amounts of both auxiliaries to center-pan a channel or varying amounts to place a channel to the right or left of the stereo image.