What might be a disadvantage of a Class A amplifier?

The characteristic of a Class A amplifier that highlights a continuous current flow without input is indeed a significant disadvantage. In a Class A amplifier, the transistor conducts current for the entire input cycle, regardless of whether there is an input signal present or not. This means that the amplifier is always drawing power, which can lead to inefficiencies in terms of power consumption.

The result of this constant current flow is that Class A amplifiers are often less efficient than other types of amplifiers. This can lead to increased heat generation and can drain batteries quickly if the amplifier is powered by them. Consequently, while a Class A amplifier is known for providing excellent sound quality and fidelity, the continuous current flow makes it relatively poor in terms of power efficiency and battery usage.