uses MMSystem;
var
Handle, Volume: Cardinal;
Details: TMixerControlDetails = (cbStruct: SizeOf(TMixerControlDetails);
cChannels: 2;
cbDetails: SizeOf(Volume);
paDetails: @Volume);
begin
mixerOpen(@Handle, 0, 0, 0, MIXER_OBJECTF_MIXER);
mixerGetControlDetails(Handle, @Details, MIXER_GETCONTROLDETAILSF_VALUE);
mixerClose(Handle);
end.