Who sais you need to use gmpc-shout for audio playback?
Enter this as command (adjusted for you use case offcourse):
?????????gst-launch souphttpsrc location=http://localhost:8000/ ! queue ! mad ! audioconvert ! libvisual_jess ! video/x-raw-rgb,width=640,height=360,framerate=25/1 ! ffmpegcolorspace ! queue ! xvimagesink
(this is for an http output running on localhost, streaming mp3 data).