I put 4 stars instead of 5 because of the price. 50 what it is I find it a little expensive but good. The key works on my PC without worries coupled with my MM400 headphones. The sound is very good thanks to the APT-X sounds obvious. A comparison with the key (its LED should be violet) and without the key allows fast realizing. Before pairing your key to your headset make sure that the key is the device's default in Windows. To do this go to the Control Panel and then click Change system sounds and in the Playback tab make the change. Otherwise your dongle will be well connected but you do hear any sound in your headphones, at least in my case.