Getting GPO to work in 64 bit Pro Tools 11 & 12
According to GPO tech support, if you want to use GPO in Pro tools 11 or 12, you will need to download a free stand alone player from Plogue called Sforzando because the Aria player that comes with GPO is not currently AAX compatible but Sforzando is 64 bit AAX compatible. Then in the Sforzando player, where you see the words "File: Empty" click and you will see "GPO" listed. Click on that to load the various GPO instruments. You cannot do multiples, though. I followed their tech support instructions and it works fine because Pro Tools recognizes Sforzando as a plug in and Sforzando can load your GPO library. The GPO library has great instruments for the price!