Sent to an audio mixer device driver after all mixer drivers have been loaded and enabled by the audio mixer manager. A mixer driver may use this message to inform the user of configuration problems (it is sent only once to each mixer device).
An audio mixer device should return zero (MMSYSERR_NOERROR) if it processes this message. The MMSYSERR_NOTSUPPORTED error code should be returned if this message is not processed by the device.