I am using a Zoom L20 mixing console as a digital interface to logic pro on an iMac and looking for help!!

Hi. I am using a Zoom L20 in a studio with 16 inputs for a band. I want to have the sound come IN to the Zoom L20 from the mics and DIs, and pass it to my iMac running Logic Pro. There I would like to use my Logic Pro effects and 3rd party plug-ins and THEN send the signal BACK to the Zoom L20 to, in turn, send the signal to my powered PA speakers.

WHY? I want to improve the sound output in my studio with full effects for rehearsal. I also want to use this setup for better recording, dubbing, editing capabilities. I am moving away from using the multitrack recording SD card on the Zoom and then manually editing it on my iMac.