Page "Amplifier" Paragraph 10

Class B amplifiers have a very high efficiency but are impractical for audio work because of high levels of distortion ( See: Crossover distortion ).

In practical design, the result of a tradeoff is the class AB design.

Modern Class AB amplifiers commonly have peak efficiencies between 30 – 55 % in audio systems and 50-70 % in radio frequency systems with a theoretical maximum of 78. 5 %.