It could be at the time that you asked there was not someone online that knew the answer. You could try asking again. :)
I looked over the Razer FAQ and the headset they recommend is the new Razer Chimaera 5.1 Wireless Headset for Xbox 360. They also had this to say:
"We can't comment on compatibility with other 3rd party peripheral providers. The Razer Onza was designed to comply with the current generation MS headsets that come with current model Xbox 360 consoles. The controller has a standard 2.5mm jack. Products with side flap connectors will not fit."