Effects loop/aux out
The Axe-Fx has a fully routable effects loop which allows you to use outboard processors anywhere in the signal chain. The effects loop can also be used as an auxiliary output for live stage monitoring through an amplifier and cabinet or as a general purpose output.
To use the effects loop as an auxiliary output the output of the block is simply not connected. Alternatively you can place the effects loop directly in the signal chain but not connect anything to the INPUT2 / EFF. RETURN jack. The Axe-Fx senses if the effects return is not used and then just uses the loop as an output.
To use the effects loop as an on-stage monitor with a guitar amp (or head and cabinet) place the loop BEFORE any cabinet simulation blocks. For example, if you want to send a fully processed, stereo feed to the P.A. system and monitor your sound on-stage you would set up a chain like the following:
AMP - CHORUS - DELAY - REVERB - EFFECTS LOOP - CABINET
Note that the effects loop is before the cabinet. The main output would then be fully processed including the cabinet simulation. If you were to send this signal to an amp/cabinet combination it would probably be excessively muddy.
If your on-stage monitoring equipment is full-range then you can place the effects loop after the cabinet or simply use the un-balanced OUTPUT1 jacks for monitoring and connect the balanced jacks to the P.A.