[JeffW]

Wait a tick... Fstop are you saying you can adjust your onstar volume with the Z1's volume conrol? I recently got the Peripheral GMAH24 and am looking at the schematic. It looks like the way it works is the sound from the onstar completely bypasses the head unit and goes out through the harness to the Monsoon, only the mute wire goes to the head unit. The GMAH24 has a volume adjustment screw on it, so I thought that was the only way to set it??