added GxTuner

snap.xml

@@ -15,6 +15,10 @@
       <connection port="system:playback_4" />
     </port>
   </client>
+  <client name="GxTuner">
+    <port name="midi_out" />
+    <port name="out" />
+  </client>
   <client name="Pianoteq52">
     <port name="out_1">
       <connection port="system:playback_1" />