- An audio network streamer is what's going to actually connect to your DAC and send it the digital audio signal.
- A server is what's going to hold all your locally stored digital audio files and make it available to the network streamer.
- You also need a mechanism for getting audio files onto your server, which is most likely your computer (but may not be).
As for what device might be best, it really comes down to what would be best for you. What works best for how you want to acquire, store, and manage your music? What streaming services, if any, do you want to use? What other devices, or audio systems, do you want to also use? What user interfaces or applications do you find the most intuitive and easy to use? Do you want to limit the number of physical boxes? etc.
We're primarily using Lumin products here after trying multiple options, with music ripped from a computer and stored on a NAS. That's been the nicest experience for us.