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
Amazon.com: Boquite Romantic PresentPower Amplifier Board, DC 8-25V Amplifier Board, 50W+50W Audio Receiver Digital Integrated Power Amplifier Board CSR8635 Bluetooth V4.0, Easy Installation : Electronics
Dave Lers : Workshop : Electronics : Bluetooth Amplifier
2x6W DC 5V 3.7V Speaker Modified Stereo Bluetooth amplifier board can connected Lithium Battery
Teaching Old Speakers New Tricks with a Bluetooth Amplifier – kavi's blog