If i understand you correctly, you want to replace your PC as a media store/player, with a standalone device.
Whatever you end up with, it will essentially be a computer of some sort, even if that computer is a small, embedded one that you don't recognise as a desktop or laptop. It has to be a computer to access the SSD/HDD, to manage the files, pull one off the disk, and convert it to a PCM stream to send to a DAC.
So the question is probably whether you want a central server, that you can access, and stream to multiple player devices around the house, or a single device that is store & player.
For a server, this could be a NAS, with some media server software on it, or ot could be a tiny computer like a RaspberryPi, with the SSD/HDD connected to it, running some server software.
You can then run a number of player client devices, which access the server, and receive media streams from it.
The control could be done local to the player device, or it could all he commanded through smartphone, tablet of computer, accessing the server, and instructing it to stream to one or more of the player endpoints.
One such server and client system is Logitech Media Server (LMS). It will run on many devices; PC, RPi, etc. It will create a library from files on a locally-connected disk, or a NAS, and will serve them to client devices. These can be LMS' own protocol, Squeeze, or DLNA, Airplay, Chromecast. You can turn any small, low-power computer (such as an RPi Zero) into a Squeeze endpoint by running the Squeezelite app. It is controlled by a nice web interface GUI, that runs on anything with a web browser. It can play different music to each endpoint, or it can group them together. LMS also supports internet radio and some streaming services.
LMS is free. Squeezelite is free.
I run LMS on a small, embedded Windows PC, running on an Atom processor. It accesses my NAS. I stream to DLNA, CCA and Squeeze renderers around the house. I can control it from phone, tablet, computers. I manage the library from a PC, ripping CDs to my NAS with Exact Audio Copy, and managing the library with MusicBee (which I also use for playing...)
@chicks has written some great posts on installing LMS under PiCorePlayer, and making Squeezelite endpoints with an RPi Xero W. Have a read of the following threads:
https://audiokarma.org/forums/index...-lms-raspberrypi-in-a-mac-environment.952521/
https://audiokarma.org/forums/index.php?threads/build-a-diy-squeezebox-touch.959324/
This is also an interesting 'journey' thread:
https://audiokarma.org/forums/index...treamer-to-mac-airport-airplay-system.937757/