Yest I did some experiements with my processor. I recorded open low E string using different amp sims in the processor and then took the graph of the soundwaves produced. But before I come out with what I found: Axiom 0: sine/cosine wave is teh purest sound wave: like a bell chime or better: tuning fork, if you have heard it. Axiom 1: None of the sound waves are pure sine or cosine wave. Every wave from a guitar string has some higher harmonics content. Axiom 2: Even harmonics added to a pure sine wave cause a saw tooth shape. Axiom 3: Odd harmonics added to a pure sine wave cause a square shape. http://en.wikipedia.org/wiki/Musical_acoustics So I recorded the clean signal. And as expected it was not a pure sine wave, but looked like sum of two or waves (2nd and 3rd harmonic) Played Overdrive, the waves beacme taller and more uniform (that is low and high volumes were equalized ---> compressed by teh overdriver) Played thru Marshall sim ---> the waves were more of teh sawtooth variety. Played thru Boogie sim ---> The waves were more of the asymmetric square variety. From the wave graphs it looked as if teh Marshall had more of even harmonic content than Boogie. Boogie had more odd harmonic content than Marshall. But from the tone, I found that Boogie sim has a tone which appeals more to me. This leads me to conclusion that: The thing about even harmonics being good and odd harmonics being evil is total baloney. Both need to be there to produce the "distorted" tone. Anyone else has had any experience on this?