4 x 50W Bluetooth+DSP Amplifier Board - TSA7804B(Apt-X)
SANWU TPA3116 2X50W Bluetooth 4.2 5.0 USB microSD Dual-CH Amplifier
Amazon.com: 2 pcs lot with charge management 2x6W can be connected to lithium battery Bluetooth amplifier board Bluetooth speaker modified board : Musical Instruments
Wireless Bluetooth 4.0 Audio Digital Amplifier Boa from elecseller on Tindie
PAM8403 Bluetooth Amplifier 10W Stereo Board Dual Channel For 18650 Battery | eBay
Teaching Old Speakers New Tricks with a Bluetooth Amplifier – kavi's blog
TPA3110 Mono Digital Audio Amplifier Module [30W]
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