Dragonfly Red: No output when selected as endpoint

I run ROON Core on a dedicated Mac Mini and want to use a Dragonfly Red as a DAC to connect my integrated amplifier to play music from Roon.

I connected the Dragonfly Red, to the Mac Mini and configured it to be the default audio output as per the Dragonfly user guide. I connect the Dragonfly to my amp with a 3.5mm Jack -> 2 RCA cable (5m) on the AUX input. Lastly, in ROON I also enabled “System Output” on the Mac Mini, so that the Dragonfly will be available as an output zone in the default configuration; EXCLUSIVE mode is ON…

I run ROON remote software on a MacBook, Android tablet and Android phone. On these devices I see the MacMini System Output + the Dragonfly as output options.

But I have the following issues:

  1. If I select Dragonfly as endpoint: I get NO sound.
  2. If I select MacMini as endpoint: I get sound.
    BUT the ROON user guide says, that in order to get high res output (DSD & MQA), the device should be set to EXCLUSIVE mode, which is not supported on Mac Core Audio. So how do I get around this?

I also have the following question:
Is it a good idea to connect the Dragonfly to the server running Roon Core? I chose this setup, because it was convenient to connect to the server and it is a fixed configuration. OR is it better to connect the Dragonfly to one of the control points (Other computer, tablet, phone)?

Thanks in advance for any tips / suggestions.