CHENBO(TM)5PCS PAM8403 module Super board 2 * 3W Class D digital amplifier board efficient 2.5 to 5V USB power Operating voltage: 2.5V-5.5V Speaker With:4-8ohms recommended:4 ohms Speaker Power :2-8W PAM8403 mini digital amplifier board Note: The left and right channel output of the "negative" can not, and then together, otherwise it will burn the IC and energized speaker (load) connected before