I’m not familiar with this equipment, but I think what they are suggesting is to disable the minidsp via airplay and enable the snd-sun8i-i2s-dac which is the networked DAC in the minidsp. You can also connect to the minidsp via USB, Toslink or SPDIF if it’s close enough to the Nucleus.
Are you using an MQA capable DAC? Roon can do the MQA decoding but not the full rendering. Still, you may not hear a discernable difference in SQ. It depends on the quality of your system and your ears.
I bought a system enhancement CD which I use often. Does it work? Dunno, but I still use it and it makes me feel better. Sometimes I think it makes a difference. Sometimes I know it’s nonsense.
One absolute certainty though; 2 glasses of red = guaranteed system enhancement regardless of which RCA cable/network/power supply/streaming protocol you may be using🍷
I may be wrong, but isn’t the minidsp a DAC? I think the D/A conversion is being done in the minidsp not the DAC in the Macintosh. I don’t think the minidsp is MQA compatible.
You don’t seem to have Roons MQA decoder on so your not getting Roons first unfold of the MQA data and the minisDSP is not an MQA DAC to my knowledge so you want get the final rendering stage. Try switching on the MQA core decoder on in Roons device settings it’s in the advanced section and set it to no MQA compatibility