I'm using HifiBerryOS on a Raspberry Pi 3B (no plus) with a HifiBerry AMP since months and I'm really happy with it.
As the Raspberry model lacks Bluetooth support I added an USB stick, and now Bluetooth is shown in the HifiBerry Web UI as source. Also the device shows up on my Android phone and I can initiate a Bluetooth pairing. But Android asks me to enter a PIN which I don't have, I can't leave it empty and simple PINs like "0000" or "1234" don't work.
Any idea what PIN to use or how to disable the PIN?