Hi Hat pedal input select

[pit21]

Hello everyone.
I have seen from the schematics and also from Dmitri's magadrym that there is a switch.On the case of Dmitri's megadrum it is labeled as Hi Hat pedal(input select).I have understood from the schematics that this switch changes the hi hat piezo signal not to go to the 4051 but to go to the Atmega?Why is that?Why do we need this switch?What is the effect if you change it?Can i even dont connect this switch or i will miss something from megadrum's potential?

Thanks!

[Synthex]

This switch can select the High impedance HiHat pedal input (atmega input) or Low impedance HiHat pedal input (normal 4051 or 4851 input).

High impedance HiHat pedal is a pedal with a potentiometer over 100Kohms.
Low impedance HiHat pedal is a pedal with a potentiometer below 100Kohms.

The PCB V2.8 has also this double input.