We recently updated to the last version of Unity which broke the FMOD integration. Updating to the latest FMOD integration package (10703_v2) doesn’t seem contain the FMOD_StudioSystem file anymore?
Nevermind, I found the migration documentation here:
http://www.fmod.org/docs/content/generated/engine_new_unity/migration.html
I didn’t realize that it was such a big upgrade.