Hi @TheCoolest, @Pelican, sorry for the late reply - didn’t get notified about your replies 
Yes to both, I have the “AUGESOUND HDMI” output selected (and bitstream passthrough works just fine, as does high resolution stereo) and “Sync Playback to Display” disabled.
When I select more than 2.0 as my speaker setup, the receiver still gets the multichannel LPCM audio (from e.g. multichannel FLACs) as stereo, and slowed down at least twice.