So Mikey,
If you wanted to put together a state of the art streaming setup, what would you choose? And why? I ask the second part because I genuinely want to understand.
Very broad question, if we were talking only about the user interface/software, and intertwining that with sound quality (because the software does make a difference there too), I think Roon is the current state of the art. Roon has recently offered the hardware too, in the form of the
Nucleus, which I've never heard. But the why part is the software, it's excellent, and it sounds superb, and it supports all PCM and DSD sample rates natively.
Roon is, like BlueOS, a finished and highly polished product. I hate their software pricing model, but that's a different discussion really.
The question is also broad in that just as I have stated earlier in this thread (as well as others), what some people call a streamer is really a server. Or, you can split that job, the server in one box residing in one particular location not necessarily near the HiFi, while the "streamer" or "player" or "endpoint" is in a completely separate box, and is located right near the DAC.
My preference is to divide those two different jobs, others insist they only want one box. You can also start out with something like an Innuos or Roon Nucleus as the streamer/player, and eventually turn it into a server only, while adding a new piece which is a streamer/player. It doesn't have to be decided once and for all upfront, the system is flexible.
Me personally, I'd run a Roon Core (server) of some sort, locate it wherever there is a network connection, and then use a Sonore Signtaure Rendu SE as the player/endpoint. I'd do so for sound quality, and the belief they have spent the budget on what truly matters, low power, low noise, and a stripped lean/clean custom Linux operating system that just sounds better. For now it would be a USB DAC, though in the future it could be an I²S equipped DAC, or even something completely different such as AoIP (Ethernet) directly into the DAC.