The web app is great for use in your house, the Spotify plugin is first class - it's supported as a target in your Spotify app, or you can browse straight from the webapp, which means even a guest on your wifi can easily pop on and help pick the music.
Another great alternative is HiFiBerry which produce their own DACs and cases that you can add a Raspberry Pi to.
Personally I have a RPi4 with the DAC2 HD and a steel case which I’m very happy with.
I think you can run Volumio on these too, but I prefer the simpler HiFiBerry OS distribution. You get AirPlay 2, Spotify and many more ways to play music. All connected to your analog hi-if equipment.
Volumio is great, but I am now using moOde audio player (http://moodeaudio.org/) which is similar, but has much better DSP, in the form of CamillaDSP (it actually works..), also I find the GUI more intuitive.
I don't mean just a lightweight plex client, but a headless plex audio sink. Plex supports , "passing" your stream session over to another client on the local network now, I'm not sure what protocol it is exactly but my Tcl Roku tv is compatible with this and its quite handy to be able to queue some stuff up on the mobile app them send it over there to play rather than fumbling with the remote and the handicapped Roku app.
https://volumio.org/
The web app is great for use in your house, the Spotify plugin is first class - it's supported as a target in your Spotify app, or you can browse straight from the webapp, which means even a guest on your wifi can easily pop on and help pick the music.