If you want build a simple Bluetooth amplifier board, AudioB plus Bluetooth audio receiver can be a good choice for your project. This is a Bluetooth 4.0 stereo receiver. It is based on CSR8635. We have used breakout pins to 2x10 2mm space male pins. You can integrate it to your project easily.
This module has a SMA connector. You can connect an external2.4G antennawith it.
Single-ended signal output with Audio amplifier
Single-ended signal output with headphone/small speakers
Differential signal output
How to use the module?
Quick press S2 to switch to the previous song, long press to reduce the volume.
Quick press S3 to switch to the next song, long press to increase the volume.
Press S1 to play or pause.
If there is audio output, MUTE pin will be high level, otherwise, will be low level.