The power amplifier can be either a voltage amplifier or a current amplifier, which should be determined according to the specific application.
Voltage amplifiers emphasize the proportional relationship between the output voltage and the input voltage, with only the voltage between the input and output.
Current amplifiers emphasize the proportional relationship between the output current and the input current, with only the current between the input and output. In general, the power amplifier needs to use a mixture of current amplifiers and voltage amplifiers to achieve stronger effects and lower distortion amplification.