ROCCAT Khan Pro Review @ Vortez
 

Inside the Khan Pro, you will find high-speed 50mm drivers that have a frequency response of 10Hz - 40KHz, entitling it to become the first gaming headset to be certified as 'Hi-Res Audio'. In theory this should mean that these drivers are capable of reproducing clear tones throughout its entire range.

https://www.vortez.net/review.php?id=1356