SMAKN&reg; TA2021 Digital Amplifier DIY Kit 12V 2ch Audio stereo Power Amp Board DC 11-14.5V Module chip: TA2021 Power supply: DC 11-14.5V 50W (OD5.5mm negative, ID2.5mm positive) Efficiency: 81%(25W, 4), 88% (13.5W, 8) Dynamic Range: 100dB Dual-channel input and output