[Paul Siegenthal]

I had the same problems.
– connecting the mic through dbx 286s directly to OBS: sound is perfect.
– connecting the mic through dbx 286s via the ATEM Mic 1 jack: high noise floor, unusable audio.

First I guessed that the bad guy was the cable. That is what Blackmagic is saying. I tried out all sorts of cables: no improvement.
The problem seemed to be in the ATEM mini itself (low-quality preamps) at first.

Then I connected my Rode Link to the Atem Mic Jack and no problems at all.

I am baffled.