AU: Macintosh HD/Library/Audio/Plug-Ins/Components/
VST: Macintosh HD/Library/Audio/Plug-Ins/VST/
VST3: Macintosh HD/Library/Audio/Plug-Ins/VST3
RTAS: Macintosh HD/Library/ApplicationSupport/Digidesign/Plug-Ins
AAX: Macintosh HD/Library/Audio/Plug-Ins/AAX/