Specifications: - Operating voltage: 2.5V~5.5V - Speaker With: 4~8ohms recommended: 4ohms - Speaker Power: 2~8W - Can use the computer USB port 5V power supply or using a mobile phone charger USB port 5V power supply battery power can also be used - High efficiency: 90% can provide 3W (left channel)+3W (right channel) output power under 4ohm load and 5V power supply conditions; Class A class B amplifier efficiency is only about 30% - Class D amplifier is highly respected today class D amplifier efficiency is extremely high sound quality won't be affected due to increasing temperature; Do not need heat sink and take less space - Noise canceling circuit was built in the amplifier board no pop noise when power on / off; With short-circuit current protection and over-temperature protection Application: LCD TVs monitors laptops portable speakers portable DVD players game consoles and phone / speakerphone Note: Must connect speaker first then power on or chip may be damaged; Do not input too large audio signal larger; Output port negative of left / right channel can not be in parallel; Max. working voltage: 5.5V