A lot of people agree with you that Roon sound quality is not optimal, hence Innuos spent 4 years developing their own software even though many of their customers, me included, bought their machines specifically to run Roon. You get the whole Megillah (Yiddish for a “book”, usually The Book of Ester - Magilla is apparently a gorilla cartoon character) from Auralic Lightning and NAD/Bluesound BluOs, which is why they are so popular.
Innuos implemented two data outputs, one using RJ45/CAT and the other usb. As the former does not provide transmit power, and has an isolation transformer built in to the socket, I assume it is effectively galvanically isolated. The usb sockets have a dedicated linear power supply. So the Zen and Zenith models have proven very popular because they provide an exceptionally good Roon output.
Of course there are additional reclocking boxes and more advanced devices like the SGM Extreme, so to get the most from Roon is really a matter of how much you are prepared to pay. A Zen Mk3 with 1TB HD is $2,850, the SGM Extreme something like $35,000.
Frankly, using Innuos, Melco, Sonore or any other device purely as a Roon server with an optical or CAT cable data link (i.e. electrically isolated) sending bit perfect data to a streamer (i.e. without any DSP) is popular as it seems to be very effective.
I’m still rebuilding, but have my ethernet and optical cables buried in the wall and ready to connect up my system to the modem. The AV, audio and internet locations will all have dedicated shielded mains supplies from a 100A phase separate from the rest of the house and its own earthing. The loop impedance is 0.08 ohms, I still don’t know what that means in reality!