Cantabile x64 requires a compatible 64-bit operating system (typically Vista x64), 64-bit audio drivers and 64-bit plugins. Alternatively, 32 bit plugins can be used with the x64 version using Cantabile's built in support for jBridge.
Note: x64 support is related to operating system and memory management. Despite the similar name, it is not related in anyway to the 64-bit audio path support in Cantabile Performer.