I was glad to see you're enjoying the Mytek with some high-eff speakers. Love the setup!
I think you'll definitely appreciate the benefit of adding a proper music server (like the Mac Mini) to the lineup. The Mytek should shine using a good USB output. It can even play true DSD rips from an SACD, as I'm sure you know.
Instead to the Mac mini, you might go the same route I have and build (or buy) a Computer Audiophile CAPS server. They play very nicely with the Mytek, and using a good player like JRiver, it can stream digital bits better than anything out there.