Unknown. I submitted a request to them a few months ago and never heard back 
From the release notes thread: Plexamp Release Notes - #23 by elan
play rap music in plexamp
play happy music in plexamp
play with a little help from my friends in plexamp
play with a little help from my friends by the artist joe cocker in plexamp
play the recently added playlist on plexamp
find taylor swift in plexamp
show me the brand new playlist in plexamp
add this track to my testing playlist
