I had the rs250 streamer/dac for almost a year and decided to add Gustard R26 external dac. The soundstage and clarity is obvious and noticable . I can listen my music at lower volume with the R26 with better sound quality. I sold the rs 250 for trying Roon with smallgreencomputer combo on the r26. I don't accept the fact the hifi rose don't want to develop Tidal connect and they stick with their buggy software. Even the free bubleUpnP is better than rose connect.
I am not a roon fan and Now I am waiting my eversolo dmp a6 streamer to join my R26 by using Tidal connect with I really like the AI for track radio and discover new artists. The nice thing about rs250 is its hdmi output, internal drive bay for music storage and vumeters. You can have the same for half money with the eversolo streamer.
So yes, adding and external dac above 1.5k$ (r26, a26, pontus 2, etc...) to your rs250 will bring you to another level.