Okay, yeah, that WAV file clearly shows the distortion on the right channel, encoded right in there.

Analysis of the file shows nothing special, other than that the file has a lot of bass. There's notable peaks at 32hz and 64hz, but nothing special about that. Correcting either of those frequencies downward sharply doesn't fix anything.

Wait a minute. Those are multiples of each other, aren't they? I wonder... Hang on...