Does the ghost react to the audio input the same it does the built in piezo or is it a different signal path. Also, It would be cool of instead of ( or in addition to ) the piezo attached to the pedal that it could be run to other objects. Id love to hear what would happen if that piezo was attached to the inside of a box or ceramic vessel.
The piezo is mixed with the main audio input before it hits the converter, so it’s part of the same signal path.
On the analog side, the piezo has its own gain control path with an analog VCA and analog switch, which lets us adjust its level and fully disconnect it from the signal path when it’s not in use.
If you want to use a piezo on the inside of a box, a ceramic vessel, or something else, the simplest approach would be to use an external piezo disc, wire it to a jack, and feed that into the audio input.