PAM8403 mini digital amplifier board, unique class D digital powerless board with non-LC filter, can be powered directly from the computer's USB. Operating voltage: 2.5V-5.5V Dual-channel stereo, 5V power supply can output 3W +3 W power, can be directly driven 4Ω, 8Ω small speakers, the output power, enough energy, good sound quality.