I set up my Raspi as A2DP sink and I am able to connect my Laptop and stream audio to the pi. Now I want to connect another device to stream it's audio signal and make FFT analysis. The problem is that the device connects and disconnects every few seconds. So can't get a stable connection. The device can connect to a simple BT-speaker and I get the sound. It is just impossible to connect the device with the pi. The device is paired and trusted and it works neither with onboard BT nor with BT dongle. Thanks for your help.