Best Caching Music streamer with onboard storage without all the pre-pro features (DAC or no DAC)

[linuxfan]

That's why in Fritzjr's other forum thread I recommended running a music server on your NAS. The complication, then, becomes which music server applications can be installed on your particular NAS model

Just for clarification and any input any of you might like to share, my NIB (2yr old?) Synology NAS is the DS923+

My comments related to whether Docker can be installed on the NAS, which in the present era is how third-party applications (which are not already provided by Synology) can be installed.
With the DS923+ you're good. In the Synology DSM interface go to "Package Center". Synology brands the Docker application as "Container Manager".

 

[linuxfan]

The nice thing about Raspberry Pi with Moode is you can customize it as much or as little as you want.

Yeah Moode is good. Though for the sake of the original poster we should not imply that only Moode has those attributes - so do many other Raspberry Pi packages;
Volumio, RuneAudio, Mopidy, piCorePlayer, Max2Play, Archphile, DietPi, RoPieee, Plex, Music Assistant ...

Also we have thrown a lot of ideas at @Fritzjr but we don't yet know what his preferred system configuration is - ie. commercial NAS + streamer/endpoint, or rPi as server, or rPi as server + NAS, or rPi as server + NAS + endpoint, etc.

my NIB (2yr old?) Synology NAS is the DS923+ with 4 2Tb enterprise drives

OK, with that pre-existing hardware I suggest Synology + commercial streamer is the best option. I'm not saying that option is better than a rPi setup - heck I replaced my old Synology DS115j with a rPi5 - I'm saying you already have a major proportion of suitable hardware.
What to run on the Synology to serve local music files? The easy option would be to run Minimserver - that's readily available in the Synology DSM Package Center. But with a DLNA server you must then use a DLNA control app, and ...

I've used both and BubbleUp looks very amateurish in comparison to the WiiM app.

BubbleUPnP is IMO the least worst DLNA control app!
So to get a better user interface, run Lyrion on your Synology - this is installed via Docker -
https://lyrion.org/getting-started/beginners-guide-synology-docker/

 

[ShadowBoxer]

Can't say, haven't used WiiM.

I think that's my point about broad statements without direct experience.

BubbleUPnP on Android makes a great control app, better than HEOS Link and the other control apps bundled with streamer boxes.