i fund it to work fine if you used it w/o the usb amplifier , just plugging the headset directly in the the controller. if you have the old controller and use a stereo headset adapter you can adjust chat and game volum mix and master volum on that , if you have the new controller you can set this in setting on the xbox .
if you want to use the usb amp plug the usb in to a power source ( like the xbox ) and then you have a few options on how to get game sound .
one is to use a 3,5 jack on your tv for game sound and then use the 3.5 jack to 3,5 jack and use the phone connection to the controller
or
get a 2,5 jack to 3,5 jack to connect the controller to the controller connection , this way you get independent volum on game and chat sound on the amp.
one of the last options will give you best sound based on testing i have done on my pc as the amp has more power then the controller can output.