I know that a lot of this has been covered here and there, but I have just been through hours of pain to troubleshoot my setup. And I wanted to share some love here so others wouldn't have to go through the same. I couldn't find a consolidated help thread that could help me out with my problem, so I did some detective work and found the solution. Hope it helps you too.
I made the decision (due to various factors) to move from Logic 9 to Pro Tools 10 on the Mac and wanted to use my Powercore X8 with it. Simply speaking I wanted the awesome sound of the Powercore that I had come to appreciate under Logic Pro 9.
So I bought the FXpansion RTAS wrapper and thought it'd be smooth sailing. It wasn't. No plugins worked. I did know that there would be some gotchas here and there (I had read many forums and readmes etc. to prepare myself), but somehow confusing behavior it all exhibited wasn't giving me a clear picture of what was going on. The erratic behavior was for example phasing sound, no sound and stuck UI. Hours of experimentation had me almost giving up on Powercore altogether and feared it'd become a new bookend. I lamented it because of the awesome sound I would miss.
But finally I got it to work, and bizarrely it works much much better than in Logic. Considering it's working within a wrapper that's pretty awesome.
This is what consolidated the various ideas of solving the problem:
Here's my solution:
* Make sure to change the permissions as described in the link above on the ROOT/Library/Application Support (top of your hard drive). There was no success for me in doing it in the user/Library/Application Support folder. You also don't need to worry about the subfolders.
* Install the FXpansion VST to RTAS Adapter.
* Re-install the latest Powercore software, 4.4.0 as of this writing.
* Open the FXpansion VST to RTAS Adapter. Don't go for the full monty "Detect and Wrap" to begin with. To experiment just begin with one or two plugins like so: Go to the Tools menu and "Detect New..." then manually select one or two plugins in the list in the window, and choose "Re-detect and wrap selected..." in the Tools menu.
* Quit the application.
* Run Pro Tools to check it.
* If you have issues try work with larger buffers in Powercore (system prefs) or in the Pro Tools audio engine.
Enjoy your awesome Powercore!
System: Mac Pro 5,1 8-core 2.4 - OSX 10.8.2 - Powercore X8 4.4.0 - Pro Tools 10.3.2.47 - Logic 9.1.8 - FXpansion VST to RTAS Adapter 2.1 - UAD-2 6.5