I know what the various amp classes are, I guess my question was unclear. If I were reviewing a piece I would not care whether it is Class A, AB, D, etc... If the sound wasn't to my liking or I thought that it sounded one way verses another amp it would be noted. I don't think the reviewer was comparing class d amplification. The sound of class D should be the same as all the others. Now, from the cheaper ones I've heard they have leaned to the brighter side of the spectrum. The Spectron Musician was the best sounding class D I've heard thus far.