Frank,
Once I saw that 2 channel was not handled well, I just used one of my MS200s as stereo source directly into the G65.

I have not paid attention to the handling of formats other than dolby atmos. I usually just throw full dolby atmos at it or 5.1 PCM.

Living Room: TV-->Sonos Arc with Symfonisk rears and twin Sonos subs. Also, a set of DSP8000SE with a MiniDSP SHD for stereo listening.
Listening Room 1: G65, DSP7000SE, DSP3300, DSP3200
Roon Core: NUC7i7