Running either Google Music or Spotify when paired with a bluetooth fm transmitter (Kinivo BTC8) I have found that depending on the music app the volume either randomly drops to a very low level or just stops the music all together. The audio is fine when listening to wired headphones. I can't isolate if the problem is with the BT/FM Transmitter or with the Bionic. I tend to think it's the Bionic, because I think I'm getting a "ghost" notification (sorry for lack of a better term). Generally I see something flash in the notification bar and the volume suddenly drops. The odd thing is, if I pause/play again, or skip to the next track (via the phone or the controls on the fm transmitter) the volume returns to normal levels. I've asked the Kinovo folks if they had any similar issues reported and they have not. (They kindly sent me a 2nd device to test and I found it had the same problem). I've tried testing without putting the phone in the car dock, but that didn't fix the problem either. It's very random, and happens about every 2-3 songs.