I just installed the OS X AU version of the Stereo Pack. Thank you for porting this package to OS X!
As I was using the plugin in Logic Pro, I noticed a peculiarity when automating the Stereo Controller via MIDI. MIDI values of 0-49 move the faders to the right of center and 51-100 move to the left. Values of 101-127 move the faders to the extreme left.
Is this intentional? I was expecting behavior similar to standard MIDI pan control (0=extreme left, 127=extreme right). The current behavior makes controlling parameters like balance, stability, or center rather cumbersome with a typical pan pot.
The MIDI automation should not be used at all with the PSP StereoPack, like with MixPack, VintageWarmer, MasterQ and MasterComp please use a standard automation with them.