Stepped Attenuator

[crackerkorean]

I am going to be building one but I have one question.

What is the difference between the 10K and the 100K resistor values.
I have read to go with the 100k as opposed to the 10K

Why is this?

 

[kyle]

If you use a 10K you will be restricted to low output impedance sources. The 100k will be a much lighter load for upstream components.