When I play an LP and stream the same thing via Spotify, it largely sounds the same between LP, dongle, and RME.
I don't have experience with LP, so no comments. But try Tidal and Qobuz. The difference between them and Spotify is obvious. Mostly the upper frequencies and the tightness in lower frequency will be noticeable. If you are not able to detect it, that's ok. Just enjoy the music.
Even a difference between the dongle and streamer should come through. At least in my system it did. I moved from Auris BluMe, to Chromecast Audio to a Windows laptop to a Windows dedicated server. And each change upped the quality of listening experience.