( Background: I was a professional musician in a past life and I was quite involved in sound reinforcement. ) No two ears, nor no two microphones have the exact same response curve. I'm not yet convinced that what you or the original comment I reply'd to can be explained by differences in curves which, AFAIK, are relatively flat in the sonic regions we're discussing. The mic I referred to earlier looks to be flat to within 3db from 200hz to 20k. Are we discussing signals outside that range or within it?