NOTE: This is "legacy" info that no longer applies to current products but may be useful to some users. Madcatz used to sell an HDMI Conversion Kit that is no longer available. This info is provided only for reference in case anyone has this cable and wants to use it.
This HDMI conversion kit doesn't have RCA stereo audio jacks. Since it replaces the standard A/V cable on older XBOX units, if an X1, X11, X3, X31 user buys this Mad Catz cable they will no longer be able to connect their headphones to the XBOX (because they require the RCA jacks). The Mad Catz cable does have an optical output, so connecting an X4, X41 is not an issue.
The oldest white-and-gray Xbox 360 models DO NOT have an HDMI port. With this particular (obsolete) model, you cannot use HDMI connections, but you can use any of our X-series headsets (using analog connections when necessary).
Current Xbox 360 models all have separate HDMI and A/V ports ("sockets") on their back panels.
Some HDMI TVs have RCA audio outputs which can be used to connect the stereo audio signal from the HDMI cable to the X1, X11, X3, X31. However, on some TVs the main speaker volume will also control the level of sound coming out of these jacks.
So if a user has a TV with this kind of volume control, turning down the speaker sound will also turn down the headphone sound, which defeats the purpose of having the Headphones in the first place.
Microsoft Support provides good info on "Description of the Xbox 360 HDMI Cable":
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