This just started recently. It happens with both headphones and bluetooth in my car stereo. On bluetooth whenever there is a change dom the system being idle to sound playing (when my stereo says av steam), there is a loud pop or crack noise. This actually happens a lot because any time there is a pause between songs on pandora the bluetooth stops the av stream. But this does not seem to be tied to pandora as it happens regardless of the app that initiates audio. On headphones it only seems to happen once if I haven't played anything for awhile.