When playing any audio (from Skype, Flash Player, HTML5) I noticed the sound gets choppy when it's above a certain loudness.
Looking at the Sound settings while playing audio I noticed a new phantom device appears when the audio is loud:
The "Headphones (Built-in Audio)" device flashes during loud sounds (it took me a few tries to get a picture). It appears to be the default device because it's selected as soon as it appears, even though I can't hear anything when it's active. If I lower the output volume the loudness threshold is increased as well.
When that happens the "Front Microphone (Built-in Audio)" device (which I do not have) disappears, making me thing it's being interpreted as an output device:
I'm using 3.5mm headphones and is perfectly capable of playing loud sounds by itself. This happens in both Unity and Gnome under the default sound settings and the "loud" here is low enough that a normal Skype conversation gets choppy.
I'm using Ubuntu 14.10 32 bits, and this has been happening since I clean-installed version 14.04.