Stereo downmixing

[mafkees1233]

Is there a way to make openbsd use 2 audio channels only?
If I play a video on vlc the voices and other mono sounds come out the left speaker and the right is used for surround effects.
Is there a way to downmix to stereo?

I've read I can use sysctl to set dev.pcm.%d.play.vchanformat=s16le:2.0 but I don't know how. After executing it it says top level name dev in dev.pcm.0.play.vchanformat is invalid