:I think the flaw in that statements is in the first part: "Some sonic qualities are easy to explain objectively ..." with the word "objectively" being the limiting adverb. I also have a problem with the use of the phrase "easy to explain". These are complex occurrences and never "easy" to describe, since they include psycho-acoustics, perception, and presumption, in addition to the known distortion characteristics. Basically ones mans distortion is another mans sonic bliss. Which leads me to the use of the term "sonic qualities", which has apparent underlying presumptions.  

 :The statement should read: "The way the human ear perceives some types of distortion can be described objectively when based on an analysis of the distortion characteristics of the gain device and/or the circuit topology."