Since Mac OS X 10.10 Yosemite, system extension and hardware drivers required to be digitally signed by the developer for authenticity. Since TC's PoweCore drivers were not digitally signed at the time, Yosemite won't load the drivers and therefore PowerCore won't work.

Luckily, a workaround to enable Mac OS X Yosemite to load PowerCore drivers ) is available (and other unsigned extensions. Here's how:

  1. Launch Terminal from /Applications/Utilities folder
  2. Copy+Paste the following line and click Enter (An Admin password is required) sudo nvram boot-args="kext-dev-mode=1"
  3. Quit Terminal and Restart your Machine 
  4. Launch Terminal, Copy+Paste the following line then click Enter sudo kextcache -m /System/Library/Caches/ /System/Library/Extensions
  5. Restart.

Before attempting to resurrect the PowerCore plug-ins with 32 Lives, please make sure the plug-ins are properly working at their native 32-bit mode in Logic 9 or other Audio Units compatible host such as the excellent Reaper