I have the 851N and wondered if you used the SOTM sms200 connected to the 851N? So you had a dsd or gigh res output from Roon/Mac combo with the SOTM in between your Mac/core and the 851.
I too love Roon but frustrated with the lack of CA compatibility.
I have my Sotm sms 200 into the USB and it works fine and just added a sonic Transporter Roon core and wow big big upgrade for $750 .
You run your ethernet cable from your router into the sms200 then out to your USB on your 851 and it recognises the sms 200 as a Roon end point and everything is fine you can then use a tablet to monitor everything or work from your core