TDA7492P Power Amplifier Chip- This is an upgraded version with TDA7492P chip. Power supply: 2.1 interface 8-25V DC power supply. Designed to optimize the circuit configuration, which can provide excellent audio output and high power. Power supply and audio input- Power supply: 2.1 8~25V DC power supply interface; Wrong polarity will burn out its chip, please note.; Audio input: CSR8635 Bluetooth chip, Bluetooth V4.0 - Stereo input for different versions of Bluetooth connection bl With DIP switch - Designed with DIP switch, it can be adjusted directly after the gain of amplifier and helps promote louder sound, which can drive higher impedance speakers. Output Impedance- Output impedance: 4/6/8 speakers /16 ohms supported (8 ohms would be best); Power Output: Added 5532 front end circuit to ensure high power output.