If you are interested, Keith Howard has written a freeware utility to apply a given pattern of distortion to a mono .wav file here: http://www.audiosignal.co.uk/Resourc...distortion.zip
It is limited in the length of signal that you can manipulate and it is restricted to a mono file only. I have some equivalent programs of my own that will work with stereo files that I might be persuaded to share. Bear in mind that for a given specified distortion pattern, the stated distortion % is only achieved for signals that are full scale. At lower amplitudes, the distortion level generally reduces (not always true). This is really rather similar to what happens in amp clipping. Low order distortion of music signals which have large dynamics mean that only the peaks are really distorted. This is another reason why hearing distortion in music signals can be harder.