Hi Brendon,
The Firmware Reference Guide can be a little hard to find at first since it doesn’t show up in the list of documentation for the surfaces or mixracks, but it has a wealth of information about operation of the console. Fortunately, once you are aware of its existence, it’s the first hit in a Google search for “dlive firmware reference“.
The block diagram on page 85 shows that aux mixes have a per-aux pick-off point selectable between: Post-Preamp, Post-Ins-A/(Pre-PEQ), Post-PEQ/(Pre-Dynamics) or Post-Delay. Then each source feeding the aux can additionally be set individually to pre-fade or post-fade. (Post-fade being after the mute stage in the signal chain.) So now we know it’s possible, but how do we achieve it?
A quick search on the word “aux” in the firmware reference manual will get us there. See page 30 for instructions on setting the source for a mix. (Hint: it’s available on the Routing screen, with the relevant Aux mix selected.)