Mainstage default mapping drum machine instrument

When I load up a patch from the patch library for a drum machine, say Roland TR-909, where are the default mappings held? The patch comes with a bunch of channel strips and when I send C1 midi note from any instrument (keyboard or drum pad), it knows to trigger the Q-Sampler on only one channel strip (Kick 1). How does it know that? If I change the mapping for the screen control that I have assigned to C1 from "Same as Input" to "Send to all" (channel strips I presume?) then it makes crazy noises. If I send it to the "Sum" bus, then it similarly makes crazy noises.

I essentially want to catch a C1 from my drum pad and change it to an F#1 for certain patches. I don't really care that the Q-Sampler has a root key of G#0... the default sound is fine to start, I just want to be able to modify those default mappings.