SOLUTION: My JBL Extreme also shuts down after exact 10min. when connected to my phone with a 3,5mm cable. Somehow it has a threshold build in the software, that when the volume suplied to the JBL-Extreme is to low, it will go standby after 10min. Issue is solved when I turn up the volume of my phone to almost maximum, and then regulate the volume down on the extreme unit. ISSUE SOLVED