Agreed. The same specs for the 818v3 list "MQA decoding and rendering". This could be where the magic is. Still, the analog signal would exit the 818 on the outputs that are limited to 192kHz. Of course, wouldn't be the first time a data sheet was vague or incorrect.

Antipodes CX + Roon, 818v3, DSP 7200SEs, 218, DSP3200s