manual/include/monitor-setup-in-ardour.html

<p>Ardour has three main settings which affect how
  monitoring is performed. The first is
  <kbd class="menu">Edit &gt; Preferences &gt; Monitoring &gt;
  Record monitoring handled by</kbd>. There are two or three
  Monitoring &gt; Record monitoring handled by</kbd>. There 
  are two or three options here, depending on the capabilities
  of the hardware.
</p>
<p> The other two settings are more complex.  One is
  <kbd class="menu">Tape machine mode</kbd>, found in the
  same dialog, and the other is the
  <kbd class="option">Session &gt; Properties &gt; Monitoring
  automatically follows transport state</kbd> setting.
</p>
<p>
  Monitoring also depends on the state of the track's record-enable button,
  the session record-enable button, and on whether or not the transport is
  rolling.
</p>

<h3>Software or Hardware Monitoring Modes</h3>
<p>
  If Ardour is set to <dfn>external monitoring</dfn>, Ardour does not do any
  monitoring.
</p>

<h2>Monitoring in Non-Tape-Machine Mode</h2>
<p>
  When <dfn>Tape-Machine mode is off</dfn>, and a track is armed, Ardour
  <em>always</em> monitors the live input, except in one case: if the transport is
  rolling, the session is not recording, and <dfn>auto-input</dfn> is active,
  the playback from an armed track will be heard.
</p>
<p>
  Unarmed tracks will play back their contents from disc, unless the
  transport is stopped <em>and</em> <dfn>auto-input</dfn> is enabled.
  In this case, the track monitors its live input.
</p>

<h2>Monitoring in Tape-Machine Mode</h2>

<p>
  In <dfn>Tape-Machine mode</dfn>, when a track is armed, its behaviour is
  the same as in non-tape-machine mode.
</p>
<p>
  Unarmed tracks however will always just play back their contents from
  disk; the live input will never be monitored.
</p>