I don't understand what role you think an Arduino might have to play in your project.
And an Arduino is not nearly powerful enough to work with good quality sound.
Bluetooth is a 1 to 1 communication system. I believe BLE can connect 1 to many but I have not been able to find any explanation of how to do it. In any case BLE is NOT intended for the high volume, long duration data that is essential for audio - that remains the role of regular Bluetooth.
...R