Email Roon and tell them you had issues with getting everything set up so you could properly evaluate the product. They’ll give you an extra 14 days.
I use Roon from my PC (the server) via Ethernet to a Raspberry Pi 4 endpoint running Ropieee. It then goes USB digital audio to a MiniDSP 2x4HD which is the DAC and also does room correction (EQ/x-over based on my own mic measurements using REW). From the MiniDSP it goes out the RCA directly to an integrated amp. Sounds fantastic. I think you could tweak your setup to work great with Roon, don’t give up yet.