Raising the input impedance?

[Léon]

Hello,

I’m considering ordering 2 of these kits, but have a question on a technical level that I’m unable to figure out myself by looking at the circuit diagram.

Is there a relatively easy way to change the input impedance of the T15 from 1.5kΩ to a value between 5 to 10 kΩ?
With “easy” I was thinking along the lines of replacing a few resistors and/or capacitors along the input path.

Thanks for your answer!
Best,
Léon