I've seen this phrase a lot lately, but I'm confused by it. Now I was under the impression that a clean tone is the primary note, with the harmonics not audible, because they are overwhelmed by teh clean note. As an amp hit it's ceiling, the primary note "clips" meaning the top of the wave-form flattens out. The harmonics are still able to get loude though, and as they do, they become audible progressively, the first harmonic first, followed by the others. Thus, high-gain sounds are naturally compressed, as all the sounds being produced by the various segments of vibrating string become equally loud. A piano has no harmonics, with only the primary note being heard, whereas a violin sound has all the harmonics audible, like a high gain giuitar sound. The lack of an attack by the bow is probably a large contributor to this, and we are all familiar with the similarity between a high-gain volume swell and a violin tone. So, unless my understanding of this is fatally flawed, how do you really get "harmonically-rich cleans" ???