Hmm, interesting question
Plugins are intended to retrieve information from somewhere if they don't already offer a feed) and so they were never really designed to be chained together like what you're suggesting.
However, there is a way you could get it to work. Every channel keeps a copy of the last feed it received in the <tt>Logs</tt> sub-directory
. So you could:
(1) Create a channel using the <i>ChangeFeedEncoding</i> plugin.
(2) Find it's corresponding file in the <tt>Logs</tt> sub-directory.
(3) Create another channel using the <i>FilterFeedItems</i> plugin but configure it to get its feed from the file you found in (2).
I'm not sure if either of these plugins support getting their feeds from a local file so you might need to stick a <tt>file://</tt> in front of the filename, or perhaps chain them in the reverse order.