If you want build a digital Bluetooth amplifier board, AudioB I2S Bluetooth audio receiver module can be a good choice for your project. This is a Bluetooth 4.2 stereo receiver module with I2S digital output and music re-sampling frequency is 48KHz. It is Apt-X supported.
It is based on CSRA64215. 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.
This product is shipped from Sydney, Australia. Worldwide shipping available- we ship to USA, Canada, New Zealand, UK, EU and Non-EU countries. Here's A Simple Do-It-Yourself (DIY) FM Transmitter Kit....