I have the Xperia Z5, and I just bought the SBS runway 4. Both (left and right) earphones are working, but the sound is mono. I understand that Android triggers mono audio when detecting a bluetooth mic. Unfortunately, I couldn't find a setting to toggle stereo and mono in Sony's version of Marshmallow, although other companies include it in the "accessibility" tab in settings. Does anyone know an app to enable stereo??