UPDATE:
Since only one extra resistor value is needed to get the higher impedances, it's been added to the kit. Now you can choose between these two options.
The input impedances on the Muffsy MC Head Amp can be changed to your liking. To help you find the right values, here's a nifty input impedance calculator.
You can play around with the values for R1, R2 and R3, and the calculator will show you what the input impedance choices will be. With all the switches set to OFF, the input impedance will be equal to R3.
The picture shows the values that are included in the kit.
PLEASE NOTE:
The resistors R3 MUST be installed, or you risk that the Muffsy MC Head Amp won't function.
Here's a suggestion for other component values, if you need a bit higher impedance:
