+ For the ALSA mixer API, the possible values are
+ determined at runtime depending on the hardware and
+ can be printed by specifying an invalid mixer channel,
+ for example --mixer-channel help. The default channel
+ is 'Master'.
+
+ For OSS the possible values are invariably 'volume',
+ 'bass', 'treble', 'synth', 'pcm', 'speaker', 'line',
+ 'mic', 'cd', 'imix', 'altpcm', 'reclev', 'igain',
+ 'ogain'. However, not all listed channels might be
+ supported on any particular hardware. The default
+ channel is 'volume'.
+ "