Does the 27" ACD do audio over USB or Displayport?

[ventro]

I'm confused by that settings dialog for the 27" ACD audio that Apple posted today.

Are they saying you have a choice to do audio either over displayport or over USB? Or do you have to do it over displayport?

To those of you with the 24" ACD, does this dialog look different from the one you have for your display?

 

[PurdueGuy]

The page states: http://www.apple.com/displays/specs.html

One cable with three connectors: Mini DisplayPort with audio support, universal MagSafe (up to 85W), USB 2.0

Not sure if there is smarts inside the display to use USB if your Mac doesn't support MDP with audio (since I don't think all Macs with MDP support audio, right?)