Hi Earl Peel,
we are a relatively new brand. when we started developing 64bit AU, there was only the latest Audio Unit (AU) Software Development Kit (SDK) available from the Apple Developer Connection (ADC). Older AU SDKs were only available from phony websites.
So we decided to go for the AU SDK that was available from the ADC website, with the limitation that this AU SDK will only build against Mac OS X 10.7 and higher.
We are sorry to let you know, that our 64bit Audio Units will not run on Mac OS X lower than 10.7.
Kind Regards,
Bastian