DX2000USB. aux send/return

Anybody know if I can put a processor in line with the usb output of the mixer.
I am looking at aux send return but it looks like this only works with the mike channels.
I need a totally 'wet' (via processor)return up the usb line.

Any suggestions

Peter

No comments suggests to me that this may not be easy. The help service 'ask Behringer' is not much help! Im hoping someone on here can help me put processing on the usb/record line on this excellent mixer.