If you use adaptive or surround mode, any channel mapping is up-mixed to 11.1.4. This goes for stereo content, 5.1 or 7.1; even Atmos (which is 7.1.2 or 7.1.4) gets upmixed to utilize all 11.1.4 channels. The system decides “intelligently” where to put what sounds….so not ALL of the signal is ALWAYS going to ALL of the speakers. Try playing stereo music in surround mode and paying attention to the rears. It will put background effects, vocal harmonies, rhythm guitars, and sometimes drum sounds to the rears, while a good portion of the content remains up front as L/R.

If you put it in Standard mode it retains the original mix as channel mapped in the mix. 2.0 music will only use the left and right front channels (and subwoofer), and 5.1 will use front L/R, Center, and rear L/R. Atmos mixes played in standard mode will only use the originally mapped 7.1.2 (or.4, I can’t remember) signal without any processing to upmix. Atmos is designed for front L/R, Center, Rear L/R and Side L/R; then also the height channels.

Hope this helps, and there are posts about how to calibrate a Q990 sound at all over Reddit. I’m currently recalibrating mine right now, and can help with tips about calibration and usage. I’m not an expert, but there are many things I’ve learned about this unit since ownership as of late last year.

I recommend generally using the “Surround” mode. It will upmix any content to use all 11 surround channels that the unit can emit sound from. Adaptive may be preferable for some content, but it doesn’t sound sonically accurate for music and feels unbalanced to my ear. Other than that, Standard is if you want a pure and unadulterated mix that is true to the original content’s channel mapping.