It’s always YMMV.
Firstly, please try a Roon rock on nuc not a Mac mini.
Secondly, The delta between an Aurender and a NUC with Roon rock and Quboz should be far greater than delta between tidal and Quboz.
Third, it really depends on the DAC, that’s my conclusion. Perhaps the Nagra DAC does 95% of heavy lifting that typically streamers do with other perhaps lesser DACs? Who knows?
by all means spend the 6k on the Aurender, but my humble suggestion would be to try a Roon rock on an nuc first. It cost as much as an audiophile usb cable for gods sake :)