What is the biggest drawback of Class A amplifiers?

Class A amplifiers are known for their high linearity and excellent sound quality because they operate with the output transistors always on, which allows for a faithful reproduction of audio. However, the major drawback of this design is that they are highly inefficient, leading to significant energy wastage.

In Class A amplifiers, a continuous current flows through the output transistors even when there is no input signal. This results in a power dissipation that can lead to heating issues, requiring additional cooling mechanisms, which can further add to the inefficiency. Consequently, the majority of the power drawn from the power supply is converted to heat rather than useful audio output, which makes Class A amplifiers less desirable for applications where energy efficiency is paramount.

While other options mention sound quality, distortion rates, and manufacturing costs, these factors do not represent the fundamental operational challenge posed by Class A amplifiers. The inefficiency and energy waste in their design is a defining characteristic that affects both performance considerations in practical situations and can contribute to higher running costs due to increased electrical consumption.