It's always frustrated me that by default you can't affect the audio sync in Plex Home Theater without bringing up a distracting menu. It's especially annoying when you have friends over and you don't want to interrupt the show because you're more obsessive over the audio sync than everyone else. I've finally figured out how to fix this. Just go to:
~/Library/Application Support/Plex Home Theater/userdata/keymaps
and create a new file called keyboard.xml. Paste in:
<keymap> <global> <keyboard> <b>AudioDelayMinus</b> <n>AudioDelayPlus</n> </keyboard> </global> </keymap>
Restart PHT and now the b and n keys will reduce and add 25 milliseconds of audio delay, respectively.