Block diagram for an analog audio amplifier,
Yes, the input resistor affects the band pass filter (or any other passive filter). So, you have three options:


You can use an active filter (where you should use an op amp or something like that). This active filter provide a very high impedance so you don't have to use a buffer between the input stage and the filter stage. Active filters also provide convenience gain control. 
If you like to use a passive filter, you can use an opamp as a buffer between the input stage and the filter stage.
If you don't want to use an op amp or any active components, you should measure the resistance of the device that generates the audio signals (input resistance) and adjust the resistances of the filter to match your required cut of frequencies. 


If you need a simple but powerful solution for audio amplification, I suggest using LM386 it is a power amplifier (not only a voltage amplifier) and it can provide gain up to 200. It is designed for audio applications. It is a very powerful IC, and easy to use and requires few components. It's just great.