Deleting an empty part about surround, moving the only article in it to 'mixing'

[ardour-manual] / include / monitoring.html

<p>
  When recording, it is important that performers hear themselves, and to
  hear any pre-recorded tracks they are performing with.
  Audio recorders typically let you <dfn>monitor</dfn> (i.e. listen to)
  the input signal of all tracks that are armed for recording, and playing
  back the unarmed tracks.
</p>