title: Is it possible to control the iOS system equalizer (so that I can affect audio playing from other apps)
body: <p>I've had some trouble sorting through all of the audio-related documentation for iOS.  I see that I can control sound EQ by using Audio Units, but I am unclear on if this is only used for audio that I play from my own app.</p>
  
  <p>I would like to build a screen that changes EQ for sound playing from other apps -- essentially a replacement for the system EQ in iOS audio settings. Is this possible? How would I accomplish this?</p>