There are a lot of options depending on what your needs are. In addition to a DAC which has already been mentioned, it's one thing if you will only be using streaming services (e.g. Qobuz, Spotify, Amazon, music, etc.) but something else if you have a digital music collection, in which case you will need a server.
If you only plan to stream from outside sources then the CXN V2 will do the job. I have three different devices like this in three different systems in my home. My office system has a Pioneer Elite N-50 network audio player. The living room system had a Lumin D2
https://luminmusic.com/lumin-d2.html and the main listening system has a PS Audio DirectStream DAC with the Network Bridge II
https://www.psaudio.com/products/directstream-dac/ . Three different pieces that all do the same job at three very different price points and three very different levels of performance. The ARCAM ST-60 and NAD C 658 are other options in this class.
If you have a music library, like I do, you will also need a computer of some type to run music server software such as JRiver, Foobar, ROON, etc. I use a PC for this with a large internal SSD though external drives can also be used. It can be as simple as a laptop or complicated like mine which is an older workstation PC used as a ROON core and dedicated to music playback. For this, in addition to Windows 10 Pro, it also runs Fidelizer 8 Pro which modifies Windows for the best audio performance. Oh, and my setup is only partway down the rabbit hole of high performance music servers.
If you use a computer server and will stream directly from it via USB, any DAC that is compatible with you music player software is all you need. For example, the DAC module of a Schiit Jotunheim 2 connected to a computer via USB then to a power amp via either RCA or XLR.
