Class-D audio amplifiers have traditionally been looked down upon by audiophiles, and in most cases, understandably so. Switching transistors for Class-D amplifiers have never had the right combination of performance parameters to produce an amplifier with sufficient open-loop linearity to satisfy the most critical listeners. This restricted the classical analog modulator Class-D systems to lower-power, lower-quality sound systems.
To accomplish the required headline marketing THD+N performance targets, Class-D amplifiers have had to resort to using large amounts of feedback to compensate for their poor open-loop performance. By definition, large amounts of feedback introduce transient intermodulation distortion (TIM), which introduces a ‘harshness’ that hides the warm subtleties and color of the music that were intended for the listening experience.