What effect does increasing the impedance of a speaker have on the power output of an audio amplifier?

Increasing the impedance of a speaker results in a decrease in the power output of an audio amplifier. This occurs because an amplifier delivers its maximum power when driving a load (in this case, a speaker) that matches its designed output impedance.

When the impedance of the speaker is raised, the amplifier sees more resistance in the circuit. Following Ohm's Law, with a constant voltage output from the amplifier, an increase in impedance leads to a corresponding decrease in current flowing through the circuit. Since power is calculated as the product of voltage and current (P = V x I), less current leads to less power being delivered to the speaker. Thus, higher impedance means that the speaker draws less power from the amplifier, resulting in decreased power output.

In practice, if an amplifier is designed for a specific impedance, using speakers with a higher impedance may lead to a less efficient transfer of energy, resulting in lower volume levels and potentially reduced audio performance.