I have no sound. I am on a Macbook Pro Retina 13" Early 2015.
I noticed this sometime after using a Fretlight Guitar and accomanying software. I am not sure if using MIDI triggered it somehow, but sound was working while I was using it.
I have no airplay audio devices listed when option clicking the speaker icon.
Under Sound Preferences, everything appears normal.
MIDI Audio setup the master volume slider is greyed out and set all the way down.
I've tried resetting the SMC and PRAM to no avail.
There is sound on boot, but abosultely nothing in OS X.
Volume controls are fine, no cross circle or red light.