Create a button that reads the registry key " AccessibilityMonoMixState" present in HKEY_CURRENT_USER\Software\Microsoft\Multimedia\Audio and shows accordingly
STEREO / push to set mono or
MONO / push to set stereo
and executes 'powershell -windowstyle hidden -command "Start-Process cmd -ArgumentList '/s,/c,REG ADD "HKCU\Software\Microsoft\Multimedia\Audio" /V AccessibilityMonoMixState /T REG_DWORD /D 1 /F & net stop "Audiosrv" & net start "Audiosrv"' -Verb runAs"' or
'powershell -windowstyle hidden -command "Start-Process cmd -ArgumentList '/s,/c,REG ADD "HKCU\Software\Microsoft\Multimedia\Audio" /V AccessibilityMonoMixState /T REG_DWORD /D 0 /F & net stop "Audiosrv" & net start "Audiosrv"' -Verb runAs"'
so it's possible to know the stereo/mono state and change it (if needed) pushing the button
THANKS!