Wireless Bluetooth 4.0 Audio Digital Amplifier Boa from elecseller on Tindie
KNACRO 2-Channel Bluetooth Amplifier Board 6W +6W Bluetooth Speaker Modified Board DC5V Power Supply Can Be Connected To 3.7V Lithium Battery-powered, With charge management circuit : Amazon.in: Electronics
4 x 50W Bluetooth+DSP Amplifier Board - TSA7804B(Apt-X)