So what would be considered the next step or steps to get a Roon endpoint with either Coax output or USB (not sure if one would be considered better than the other).
I can only say that I have recently moved from Pi3 + HAT (IQaudIO Digi+ coax) to Pi4 native USB, without noticing any difference in my A-B tests. I am using a RME ADI-2 DAC.
My suggestion is to buy a Pi4 and make a test on your own: probably you will decide to sell the Node…
I’ve actually just moved to a RPi 3b+ with Allo DigiOne sig. from the bluesound node2.
I find I get a bit more resolution, detail without any hardness.