Mac Mini Vs. Bluesound Node 2.

The Mac mini via USB will be entirely dependant on the SQ of the USB DAC and ancillary equipment.

As the question currently stands, it cannot be answered.

Well, this is what confused me in watching you tube vids and reading up, because in one vid, someone plugged the mac mini into a chord DAC, they also plugged the Node into the same chord DAC, and the mac mini sounded better. I would have thought SQ in this case would be more dependant on the DAC, but apparently it is not? 

Use a different DAC and you could get a different result, amongst other things it depends on the specific timing of USB data and control packets from the device and how the DAC handles these.

Also you didn't specify that the output of the Bluesound Node was via USB and an external DAC; it's internal DAC and analogue circuitry is actually quite good (at its price point its analogue output is one of the best).

I started off streaming with a Bluenode 2 in to my Naim system it sounds very good ( then I moved to ND5XS), the kids use it in their bedroom. I'd have the say the app for the Bluenode is much better than the Naim app on android.