Test the sound output as well

[suntong]

Hi,

Now that we can switch to different sound outputs, it'd be trivial to add a feature to test sounds played through those different outputs, would it? Would you consider adding that feature pleease? This small adding will be hugely helpful to me, as I've exhausted my searches for an application to test sound outputs, especially my HDMI. (Yeah, I found gnome-media, but that huge package is really an overkill just for simple testing)

Thanks!!