USB headphones (PulseAudio)

Connect your USB headphones to the Pi and then run:

pactl list

In the output of pactl list, you will see a list of sinks. Each sink has a Name and a Description. The Description will usually contain the name of the device. For example, if you have a USB headset, the Description might be USB Audio Device.

Set the sink (for example, sink #2) as the default sink:

pactl set-default-sink 2

Then, try to unsuspend and activate the sink:

pactl suspend-sink 2 0

You might also want to unmute and set the volume of the sink:

pactl set-sink-mute 2 0
pactl set-sink-volume 2 80%

If you want to test if the sound is working, you can play a test sound:

paplay /usr/share/sounds/alsa/Front_Center.wav