A terminal device, wherein the terminal device comprises: • an access unit, a processor, a digital-to-analog converter, a built-in first power amplifier, and a detachable second power amplifier, ∘ wherein the access unit is a secure digital, SD, card socket, wherein the SD card socket is provided with pins, and ∘ the detachable second power amplifier comprises: a substrate, a power amplifier disposed on the substrate, and pins on the substrate, wherein the pins on the substrate are connected to the pins on the SD card socket after the substrate is plug-connected to the SD card socket, wherein: • the access unit is connected between a headset or an audio speaker and the digital-to-analog converter, and is configured to enable an insertion of the detachable second power amplifier; • the processor is configured to: detect whether the detachable second power amplifier is inserted into the access unit, send a first digital signal to the digital-to-analog converter if detecting that the detachable second power amplifier is inserted into the access unit; and send a second digital signal to the digital-to-analog converter if detecting that the detachable second power amplifier is not inserted into the access unit; and • the digital-to-analog converter is connected to the processor, and is configured to: if receiving the first digital signal, convert the first digital signal to a first analog signal and send the first analog signal to the detachable second power amplifier; and if receiving the second digital signal, convert the second digital signal to a second analog signal and send the second analog signal to the first power amplifier. • an access unit, a processor, a digital-to-analog converter, a built-in first power amplifier, and a detachable second power amplifier, ∘ wherein the access unit is a secure digital, SD, card socket, wherein the SD card socket is provided with pins, and ∘ the detachable second power amplifier comprises: a substrate, a power amplifier disposed on the substrate, and pins on the substrate, wherein the pins on the substrate are connected to the pins on the SD card socket after the substrate is plug-connected to the SD card socket, wherein: ∘ wherein the access unit is a secure digital, SD, card socket, wherein the SD card socket is provided with pins, and ∘ the detachable second power amplifier comprises: a substrate, a power amplifier disposed on the substrate, and pins on the substrate, wherein the pins on the substrate are connected to the pins on the SD card socket after the substrate is plug-connected to the SD card socket, wherein: • the access unit is connected between a headset or an audio speaker and the digital-to-analog converter, and is configured to enable an insertion of the detachable second power amplifier; • the processor is configured to: detect whether the detachable second power amplifier is inserted into the access unit, send a first digital signal to the digital-to-analog converter if detecting that the detachable second power amplifier is inserted into the access unit; and send a second digital signal to the digital-to-analog converter if detecting that the detachable second power amplifier is not inserted into the access unit; and • the digital-to-analog converter is connected to the processor, and is configured to: if receiving the first digital signal, convert the first digital signal to a first analog signal and send the first analog signal to the detachable second power amplifier; and if receiving the second digital signal, convert the second digital signal to a second analog signal and send the second analog signal to the first power amplifier.