SONY DSX-S300BTX car audio unit is bugged, or at least it doesn't do what sony markets. It should be compatible with iphones and should make it possible to listen music from your iphone and have your iphone integrated for telephony at the same time but in real life, it isn't really possible.
Thing is that every time you connect the iphone via bluetooth while it is already USB connected and playing music, it will mute the music and you'll have to replug iphone to get the sound back. That wouldn't be problem, cause you could always first bluetooth connect the phone and then hit play but bluettooth signal losses happen from time to time during drive and unit automatically reconnects the devices - only problem is that each auto reconnect again mutes the music. So Sony DSX-S300BTX experience is one annoying torture.
This bug is probably caused by the fact that sony always connects iphone as a bluetooth phone and bluetooth audio device at the same time and that "bluetooth audio device" connection is the cause of USB music sound loss. Since I didn't find any way to prevent iphone from connecting as a bluetooth audio device along with bluetooth phone I can only conclude that someone at Sony forgot to test the device before putting it on the market.
Nice job Sony, you should give a raise to people who created this device...
I have many Sony products but in future will definetly try to avoid your products after this experience.
