Hi @Jak2555
A&H protocols are layer 2 which means the units are not addressed and so you wouldn’t be able to split out the signals between the Qu and the AR2412, but you can use a PoE switch directly before a ME or multiple ME units. i.e. wherever a ME unit could be connected, including the Monitor or Expander port of the AR2412 as you say.
https://support.allen-heath.com/hc/en-gb/articles/4403292650641-ME-Compatibility-with-third-party-switch
It would need to be a fast ethernet 100MBit switch if connecting to an SLink port (as if the SLink port detects a gigabit connection it will automatically go into gigaACE mode), but connecting from the monitor output of an AR2412 you should be fine.
Cheers!
Keith.