The problem

I have a new M1 Mac mini connected to a Philips monitor, connected via the Thunderbolt (USB C) port. Whenever the Mac wakes from sleep, the audio is not working and is fixed by toggling the following setting: Audio Midi Setup > Format

I can see that there is an error, but there's no tooltip to explain what it is.

Philips audio settings



Mac mini M1 with 16Gb and Mac OS 11.1


Philips 499P9 with a built-in docking station, featuring:

  • Audio
  • Ethernet (which appears as USB Ethernet in Network settings, but won't connect)
  • Multiple HDMI and USB C inputs
  • USB B connector for HDMI 1 device
  • Multiple USB A ports for shared peripherals (keyboard, mouse, headsets, etc.)
  • Do you have anything non-Apple in your audio setup? I had similar issues through Sierra/High Sierra which eventually "just went away" by Mojave. I blamed my 3rd party pro audio drivers, but there was never any real conclusive proof.
    – Tetsujin
    Commented Feb 4, 2021 at 18:28
  • Where does the audio fail, on the Mac mini, or on the Philips 499P9?
    – IconDaemon
    Commented Feb 4, 2021 at 18:37
  • From what I've seen at the Phillips website, this is monitor is designed more for Windows, than macOS. So it's not surprising there are issues. At the moment, I'd suggest automating the repetitive task of toggling the setting using AppleScript. Commented Feb 4, 2021 at 18:56
  • I also have a USB headset adapter (for connecting a professional telephony headset) which works perfectly. Commented Feb 5, 2021 at 10:42
  • The Philips has worked flawlessly with my ChromeOS tablet (via USB C dock) and my Ubuntu PC (connected via the USB B). Connecting it to the Mac is the first time that I've encountered these issues. Commented Feb 5, 2021 at 10:43

1 Answer 1


The Exclamation mark in a speech bubble is not an indication of an error, but shows which audio output is configured for system alerts and sound effects.

Having said that, I've experienced problems with external audio after sleep on my 2018 Mini. I suspect it's a bug. I have to kill the coreaudiod process to get things working again.

sudo killall coreaudiod

Then enter an admin password.

If you are changing the Sample rate to get things working, then it may be that doing that restarts coreaudiod. (Assuming it's the same issue.)

Note that some audio apps may crash or get confused if you change the sample rate while they are running.

  • 1
    is that the new icon? I don't have Big Sur to see. Always used to be 'Mac Face' system, mic for input, speaker+waves for output, though I don't have a display that registers as a DP output.
    – Tetsujin
    Commented Feb 11, 2021 at 11:49
  • 1
    Yes, fraid so....
    – benwiggy
    Commented Feb 11, 2021 at 11:50
  • 1
    Thank you for letting me know about the exclamation mark. Normally, I'd associate this with a warning or an error. I'll try sudo killall coreaudiod. However, toggling the sample rate is easier than typing my password. From what I've experienced, I haven't had any app issues when toggling it, so far. Commented Feb 11, 2021 at 16:23

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