I believe the Waves Soundgrid card could work too, but the Dante card gives you more options to route the audio to many more sources. Technically if you only need the audio to go from your mixer to your iMac, you can plug a standard CAT5/CAT6 ethernet cable into the Dante Card and straight into your iMac’s ethernet port.
I suggest you watch (if you haven’t already) the Dante YouTube videos to see the capabilities of the card.
In my opinion, the Dante card gives you the best options available.
Robert