There has been a lot of talk about this in Innuos Zen owner’s forums. The zen runs LMS as default but can also run Roon core, Roon endpoint, or a combination of both (experimental mode) via squeezbox. In that mode it sounds better than in the other Roon settings. This has been confirmed by almost every Innuos owner that uses Roon. So this is not just something in one’s head. There is a real SQ difference when playing Roon via Logitech squeezebox.
I decided to revisit this again and I’m back to using the Squeezelite connection thru with my Stack Audio Link II streamer. I tried the track “Black Math” by the White Stripes and there is a clear difference between Squeezelite and the roon endpoint setting. The electric guitar just sounds much more engaging with Sqeezelite. Also the way the sound fills the space is better with Sqeezelite. Sounds more organic. I kind of surprised I heard as much difference because in the past it seemed more subtle. I have recently swapped out stock power supply for linear one with my streamer and that has improved transparency.
My setup is the Focal Arche, Focal Utopia with Danacable Lazuli Reference cable, Stack Audio Link II with linear power supply. The streamer is using commercial version of RopieeeXL, so anyone with RPi endpoint can try out Sqeezelite setting activating it on the setup and then turning on Sqeezebox support in roon and choose it as endpoint.