What are you using the mixer for – recording.
Do you need a stereo input to the FX unit? Yes
With my analog mixers and processing racks of equipment
I always took a mono single aux output to an FX unit and then
took the stereo FX out back into the mixers stereo input/return
channels. Wouldn’t this be a mono copy and not true stereo?
I’m going to say your option B is the best way to go. Thank you.
The FX insert connection your tried created a feedback loop.
The stereo output insert jacks are more for inserting an EQ and or
a compressor limiter on the overall mix output. Rats! I’m definitely not selling off the little mixer I was using because it was so easy yo have a global FX SND/RTN. Maybe I can still use it’s master outs to the ZED…just “thinking out loud” on that idea.