Sound Channels:

  These 4 buttons are used to turn the amiga sound channels on or off. This
  is used when you want to accompany the module.
  (See the Sampleinfo window).

  Please notice that these buttons indicate the  hardware  audio  channels,
  which  means  that  if  a  noteplayer  is playing, pressing the channel 1
  button can turn of upto 8 channels.

  Ofcourse they can be used for fun too!

  You can also use keyboard to control this feature.

  NOTE: It's  not  all moduletypes which supports turning off channels e.g.
        the 7 channel TFMX-player. See the Module type section.