+<p>
+ The rationale for pre-processing with I/O plugins is that it's a more
+ lightweight way to do it as compared to busses. Much of that is because busses
+ have automatable parameters such as fader and panner positions, as well as
+ plugins' parameters. Evaluating parameter automation (even when there's none)
+ adds additional load to the CPU. However I/O plugins are not automatable, so
+ there's no evaluation happening. As far as Ardour is concerned, they are
+ almost like JACK audio server clients running alongside Ardour.
+</p>
+
+<p>
+ Another use case would be loading an instance of the NDI Input plugin as a
+ pre-processing plugin to be able to capture and mix sources from NDI devices,
+ or loading an instance of the NDI Output plugin to send audio from Ardour over
+ IP to a receiver for broadcasting.
+</p>
+
+<figure>
+ <img style="width:50%;" width="50%" src="/images/io-plugins-ndi-input.png" alt="NDI Input plugin loaded as a pre-processing I/O plugin">
+ <figcaption>NDI Input plugin loaded as a pre-processing I/O plugin</figcaption>
+</figure>
+
+<p>
+ It's also possible to use the post-processing section to load plugins for room
+ correction or signal analysis (VU meters, spectrum analyzers etc.).
+</p>
+