If you're bothered by low volume while listening to music from your iphone over bluetooth, and find you have to turn it up to 8+ to get decent volume, this fixed the problem for me. Got to settings-->music and then de-select the "sound check" option. Your volume level will increase substantially. Also, as an FYI, don't forget your EQ settings in the phone will greatly influence sound quality for music played over bluetooth. For those with premium sound as I have, you may want to select none, and use the adjustments in the car to customize the sound.