I started with a Bluesound Node 2i and later added a Benchmark DAC 2 HGC and the sound quality improved significantly with an external DAC. I recently sold the Node and replaced it with an Aurender N100H streaming server. The sound quality has again improved, albeit not as much as adding a DAC initially did, but it is noticable.
The Aurender Conductor app is also a much more polished interface compared to the bluOS app. I stream from Qobuz and Tidal and also have some local files stored on the Aurenders internal drive and it all works together seamlessly. The Tidal and Qobuz integration in the Conductor app is more complete than it is in blueOS in regards to auxiliary features. I find it easier to browse new music, playlists, suggestions, etc.