This is exactly what I am facing, on my mobile devices I use Plexamp, but at home I still need Roon.
Besides, if Plexamp wants to grow their user-base there must a better solution than a Raspberry Pi.
There are a lot of non-technical users or users who don’t want to experiment with a Pi and don’t want to spend hours to get it to work.
I can find my way with a Raspberry with Roon (used it for a bunch of endpoints without any trouble) but I have trouble to get it running with Plexamp (Plexamp Raspberry Pi and Allo Digione).
I sincerely hope there will be an integration with wiim or something else.