Fortunately, all the three headsets are capable of playing back music even at this comparatively high volume without noticeable distortion as long as you don't do any kind of bass boosting, which could very easily result in distortion. This may also mean you will have slightly (but not much! A2DP lets you stream stereo audio to other devices over Bluetooth; for example, so you can listen to music and other audio through wireless headphones or speakers or a Bluetooth-equipped car audio system without having to connect any cables. We briefly covered this new functionality in our review of the iPhone 3.0 software , but here's a more in-depth look. You can now listen to your favourite music on high fidelity stereo headphones, without that annoying cable attached to your music player. The new Bluetooth Headphones have frequency responses similar to those of wired studio-grade headphones.