LTSPICE interpolates any loaded .wav-file. This is a problem when digital filtering will be applied.

There are two chances to get "staircase" voltages.

1. Sample the wav-source with short gate times. 
   This is what's done in the example file "Wav-SH1.asc".

2. Make a PWL source file from the .wav file. This will require to write a
   program which translates the .wav-format to SPICE PWL-format.

