Welcome.
This is Digitone category, but AFAIK they behave similarly in that concern.
I did it recently. It’s possible with DN, mono send with hard panning, but it is mono left or right, not confortable with headphones (I used a mono adaptator).
You can consider Output Left as main out, and Output Right as send.
Pan left what you want dry, right for wet.
Output Right > Fx in
Fx out > Input Left
Hard pan left Input Left and increase it’s level.
If you don’t understand, just send me your OTO Boum and I’ll show you. 