For completeness I will note:
In Windows Vista and up it is possible to gather some information about the
volume taper via public APIs:
1) call IAudioEndpointVolume::GetVolumeRange to get the min/max/stepping values
(e.g., -45 dB to 0 dB in steps of 1.5 dB)
2) set each stepping value in turn via
IAudioEndpointVolume::SetMasterVolumeLevel (e.g., -45 dB, -43.5 dB, -42 dB,
..., -1.5 dB, 0 dB)
3) query IAudioEndpointVolume::GetMasterVolumeLevelScalar after setting each
stepping value to see what scalar value corresponds. (0, ..., 1)
4) plot the pairs of points and notice the resulting curve; it is indeed a taper and not
"linear in dB"
