@Gaf
As far as I understand it, the MQA DAC is in the 218.
I don't know if your processor has DSP / Room-correction, but if it doesn't, then (as far as I know) the 218 could make your Auralic entirely redundant, although I might be wrong.
You'd run Roon from a Core & Remotes, connect the core to your home LAN, connect the 218 to your home LAN, tell Roon that the 218 was your Roon endpoint (or one of your many endpoints) and hopefully - with a software update - control the volume & switching through (Roon or) your processor.
You connect your speakerlink (output) from your processor to the 218 input, and the output from the 218 into your DSPs.
Does that make sense ?
It's the same as I'm going to do for my 861v8 processor - the 218 seems the simplest way to get full-fat MQA into my DSPs....
It makes sense and I think we can use the same connection with the 818v3. I don't know if it works well with 2 channel and multichannel material. I will take one 218 when available to do some test.