This review is from: HDMI Cable & Audio Adapter for Xbox 360 (Video Game)If you have an external sound system (be that speakers or Turtle Beach headsets) then this is the trick if you cannot get it to work any other way.
I bought some Turtle Beach X11's and because I use the HDMI the piggyback cables don't apply.
Firstly, though, check to see if you can use your TV's audio out - it works for some TVs but not others. If you cannot get sound then you will need this cable.
It may be helpful if I say this is a HDMI Audio Cable (as it is called by Turtle Beach).
The slight problem is the Xbox reseting if you switch off the TV, but it is not an issue for me.
The HDMI cable is fine, I changed my old cable to this one and it is good. Though, the HDMI cable is more a bonues feature rather than the main product.