This paper discusses a new kind of distortion mechanism found in transistorized audio power amplifiers. It is shown that this distortion arises from the multistage feedback loop found in most high-quality amplifiers, provided that the open-loop transient response of the power amplifier is slower than the transient response of the preamplifier. The results of the analysis are verified by measurements from a simulated power amplifier, and a number of constructional rules for eliminating this distortion are derived. Manuscript