I do have this problem as well, and I also contacted Razer about this. This is what they said:
The buzzing sound you are hearing is caused by the USB connection within computer systems that have a grounding issue and not due to the Razer Kraken 7.1 headset. Some USB ports will cause this so we recommend switching the USB cable to a different USB port on your rig. If all your USB ports show the same buzzing sound, you may need to purchase an AC to USB converter (sold separately). On laptops the buzzing sound may be slightly louder because of the way the USB ports are connected internally.
Please note, If you turn up the volume of the Razer Kraken 7.1 to higher levels and have no audio playing you may still hear some hissing. Unless it is abnormally loud and still audible when audio is played through the headset, this would be considered normal and you will notice this sound when using any high quality analog headset that is capable of reproducing these higher frequencies.
Try to mute your mic, the headset is probably configured to play back whatever the mic picks up, which would create a constant background noise [because the audio output would ALWAYS be open, even if the mic volume was set all the way to the bottom]. So check Windows to see if the mic is set to playback whatever it picks up.
Is there other USB devices connecting to you PC?
Try disconnecting them one by one to find the cause of the static noise.
Some USB devices may cause the static noise in your headset.