So apparently many macbook pro models have a digital audio output hidden inside their 3.5mm headphone jacks. Example.

I thought this was physically activated by the mini TOSLINK plug, but recently I installed Linux Mint (native boot) on my MBP and that red light came on and stay on.

So I guess it can be controlled by software.

Anyone know how to activate it in macosx? The only reason I want to turn it on is I think it looks cool.

  • 1
    I could imagine you can activate digital out in soundflower
    – n1000
    Feb 15, 2017 at 9:01
  • 1
    There was a common issue with hardware on MacBook Pros where the switch would fail and leave the light on permenantly. Do the headphones work at all in macOS? Feb 24, 2018 at 0:34

2 Answers 2


Plug in a clear audio jack and you’ll have your red laser engaged and the sound muted. It’s controlled by firmware which is software, just harder to patch and mess with.


Blow into the audio port with canned air or similar to remove any dust collected there.

  • 1
    This may need some more explanation on the effect and why this solves the problem described in the question.
    – nohillside
    May 6 at 21:33

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