Power supply: You can directly use the MICRO USB Android cable 5V for direct power supply, or you can also connect 5V power supply or 3.7V lithium battery (as shown below). Note that the 5V and 3.7V power supply interfaces are different. The 5V voltage is connected to 5V and GND, and the 3.7V lithium battery is connected to VBAT and GND.
Audio output: The earphone can be directly connected to the 3.5mm audio interface, or it can be wired for the audio input of the power amplifier board (the interface L/R/AGND can be directly wired as shown).