There’s some strange issues in the PluginHost (OS X only):
First of all, I always hear the input of my soundcard, even though I did not connect the Input & Output graphs. This is not really important for me, I just wanted to say that there’s this bug. It does not appear in my own application.
Many AudioUnit plugins don’t seem to get any input, so they don’t produce any sound, although exactly the same plugins work as VST version. Example: Audio Ease Periscope from the Nautilus Bundle.
When I put in some plugin, there seems to be a feedback delay in the audio, even if the plugin does not produce any sound (see point 2.)