In the S4, when headphones are put in, when a notification occurs, the sound plays through both headphones and external speaker at the same time. Is it easy to disable the external speaker entirely when headphones are connected? Also, on my old Razr MAXX with v4.1.2, notification sounds would overlap music - is it possible to re-enable this on the S4? Right now, notifications halt the music to be played and I miss the overlapping effect... Thanks!