I connect my Dell XPS 12 Ultrabook running Windows 8 into a Dell 2408W monitor's HDMI port using a mini display port to hdmi adapter, the one Dell sells. The display is just fine but the audio does not come through the HDMI port to the speakers connected to the 2408W monitor. The audio comes out of the XPS built in speakers.
I can connect my AppleTV to the 2408W monitors HDMI port and the audio from the AppleTV comes through the speakers connected tot the 2408W monitor just fine.
If I connect the Dell XPS 12 into a Panasonic flat panel TV's HDMI port, the audio comes from the TV just fine.
What am I missing?