@andypiper Hi,
i just tried with my Sony XB41 loudspeaker.
i launched the pairing on it, i launched a research of BT devices in the pad menu in recalbox, when it was found in the list, i chose my XB41 speaker, it automatically paired.
In the sound menu, you can also find the speaker (or headphones) once it's appaired. Just select it if it's not.

Look for an aptx x ll dongle. best paired with supported Bluetooth headphones.