Replace Mac mini with another Ethernet source-what?

[ICUDoc]

Hi.
I am a little embarrassed to ask, but I am unsure what to CALL the device I want / need. I don't know if it's called a server or what.

Roon is very slow on my old Mac Mini, and I can't make remote from my phone work reliably and the "transport in use" error is driving me crazy.
For these reasons, I want to find a device to:

-Be remote controlled from my iPhone, iPad or MacBook
-Run Roon
-Source music off my outboard hard drive
-Feed that to my Devialets via Ethernet 

Bonus features:
-GUI on the TV sometimes 
-Source from a streaming service e.g. Tidal, Spotify
-Ability to rip from CD to the hard drive.

I hope this is achievable!
I am no longer cash-rich so I am trying to keep this well under 1000 dollars (I'm in Australia).
Thanks very much for any contributions e.g. is The Audio Alchemy DMP-1 the sort of thing I want?
thanks and kindest regards
David.