The only qualifier I can add is that I have to leave the Roon volume setting as Fixed Volume for MQA/MQB to work. If I choose DSP Volume or Device Volume, I loose the MQB/MQA icon on the S2 display screen. That said, in the Fixed Volume setting I can still adjust output volume with the supplied remote control, or of course at the amplifier.
My trials and tribulations are documented here, Pro-Ject Pre Box S2 Digital setup, with a big shoutout to Sean2016 for his help.