UR824 standalone with external effect, how? [You can't]

Without any DAW running, is it possible to set up an external effect and use it like you would with a regular mixer?

For example:

Synth1 L/R OUT -> UR 824 IN 1-2
Synth2 L/R OUT -> UR 824 IN 3-4
Synth3 L/R OUT -> UR 824 IN 5-6
Effect L/R OUT -> UR 824 IN 7-8

UR 824 OUT 7-8 -> Effect L/R IN

And then (in dspMixFx) portion out how much effect you want on Synth1, Synth2 and Synth3, like a regular SEND on a mixing board.

If so, how?

"Dear Mr. God,

Unfortunately that’s not possible. The send is “hardwired” to the DspMix
FX.

Best regards,

Albert Einstein
Technical Support"