I have a streamer/dac, lumin x1, and A nucleus for roon. And this connects into my Gat cj pre-amplifier. The lumin is superb and using a separate Dac which I have I wanted to avoid due to all the additional interconnect crap and all the temptation to periodically replace the dac. I don’t find this necessary anymore and see no value in doing it. So the inclusion of a dac within the streamer in this case ideal and it took a while to find it and was well worth the search.
a Streamer does mystical things that most have no clue about. The nucleus houses an operating system necessary to operate roon. And then you got the endpoint within the streamer that again does mystical things to allow all the necessary machinations to transform Data flow coming in from the nucleus. I think it Hass to do with a bitstream and clocking and changing the compression rates and all kinds of crazy stuff and no one really understands except those few who actually do.
Do you need a streamer to do quality work on your music? probably yes.