I suppose that I could wire my mac mini using a usb cable to my Hegel and get streamer level quality without buying a dedicated device?
Try it. What do you have to lose if you already have the Mini? I've used this setup (with different amps/DACs) and it works fine. You can host Roon Core on a Mini (or other full-function computer) as well as Audirvana or (of course) Apple Music. Turn off Time Machine (or schedule it to run at night) and other process that might interrupt the music stream.
In my opinion, your choice of streaming platform may be best dictated by the services you want it to support and how you want to control it. With a full-function computer (like the Mini) you have many options. After you've experimented with a few, down the road you might want to add a dedicated streamer. If by then you've decided (for example) you like Roon, you can focus on Roon-Ready streaming devices. In that case, one of the Rendu products would be an option; Aurender (at this time) would not be.