As part of the work to make alsa and pulse audio device selection working. I created a widget that gets a list of alsa devices. I'm planning on extending this to pulse devices as well. Not sure how I want to do this completely yet. But I have some ideas forming.
I think the main idea may be that rather than selecting the mplayer ao device. The user would just pick the device from list and would not need to worry if it was a pulse or alsa device. I plan to have a "Default" option that will use whatever mplayer is either configured for or whatever it detects. That allows legacy stuff to work correctly.
Screen shot, showing the widget with the devices it found on my computer. I have noticed that the order of the devices may change from boot to boot, so I may need to sort the list.