This stereo Bluetooth headset is a perfect addition to a A2DP enabled phone (I have a MOTO RIZR). A single charge usually gets me through an entire week of heavy usage.The A2DP protocol digitally compresses the audio stream before sending it to the headset, so if you use 128Kbps CBR MP3/AAC (e.g. iTunes), you will notice reduced audio quality. However, a high bitrate VBR MP3 plays beautifully.I love this product so much, I refuse to buy an iPhone, because Apple refuses to support A2DP (probably because it makes their crappy low bitrate music sound terrible).