The option "Output stereo to all speakers" in "Audio Output" should also output mono to all speakers.
Or add another option for mono, although IMHO it is safe to assume that if one wants stereo to be upmixed, he wants mono to be umixed too.
Or add another option for mono, although IMHO it is safe to assume that if one wants stereo to be upmixed, he wants mono to be umixed too.