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Class AB amplifiers are designed to combine the benefits of both Class A and Class B amplifiers. While Class A amplifiers provide higher fidelity audio reproduction due to their continuous conduction of the output devices, they suffer from lower efficiency, leading to excessive heat generation and power consumption.

Class AB amplifiers address these issues by allowing the output devices to partially turn off during parts of the audio signal, which enhances efficiency while maintaining a high level of fidelity. This means that Class AB amplifiers operate with reduced distortion compared to Class B amplifiers, which can introduce crossover distortion due to the abrupt transition when switching between output devices.

By implementing a biasing scheme, Class AB amplifiers ensure that both channels contribute to the output, resulting in a smoother transition and minimizing distortion at lower power levels. This makes Class AB a favorable choice for audio applications where both sound quality and efficiency are important, thus placing it higher on the fidelity scale than Class B, yet not achieving the same level of efficiency as Class B, which operates the output devices in a more efficient manner but compromises on sound quality.

Overall, Class AB amplifiers strike a balance between these factors, delivering superior sound quality without the heat and power drain associated with pure Class A operation.