@tony1954 , good point.
you have some decent equipment going into the game.
My 2 cents-
What is the input cabling? How does it arrive at the DAC?
I second getting a good streamer. Aurrender and Innuos are two very good brands.
I have no experience with Apple products, but from a short Googling, it looks like the Mini Mac isn't expressly designed for music reproduction, leading me to suggest products made for the task. Though some might disagree, I believe that there is a difference in how digital audio products are made vs. generic.
HTH
Bob