While it’s connected, the iMac shows up as a speaker on the Mac you work on, under its own name. What your Mac plays can come out of the iMac’s speakers, as from any speaker.

Turn it on

On the Mac you work on, do any of these:

  • Turn on Sound under the display in the Second Display menu, in the menu bar.
  • In Second Display Settings › Sound, choose the display from the Play sound on pop-up menu.
  • Choose the iMac in Control Center or in System Settings › Sound, as you would any speaker.

The first time, Second Display installs its sound device. macOS asks for an administrator’s password, and sound on the Mac you work on stops for a moment.

Volume and mute

  • The volume keys and mute of the Mac you work on set how loud the iMac plays, as for any speaker.
  • The iMac keeps its own volume, which you set on the iMac.

One display at a time

One display at a time plays your Mac’s sound. Turning on Sound for another display moves it there. An app with its own output menu can still play on any of your displays.

When several Macs use the same iMac, it plays the sound of each.

Headphones

Headphones take the sound back when you connect them, as they do from any speaker. To play on the iMac again, choose it in Control Center or turn on Sound again.

Remove the sound device

Choose Remove… next to Sound device in Second Display Settings › Sound. If you deleted Second Display first, the sound device stays on the Mac without any speakers: open Second Display again and remove it there.

If something doesn’t work

  • No sound from the iMac. Check that the display is connected and that Sound is on for it in the menu, or choose the iMac in Control Center. If headphones are connected, they have the sound. Check the iMac’s own volume too.
  • macOS asks for a password. Installing the sound device the first time, and each update of it, needs an administrator’s password. If the menu says “Update the sound device to play sound.”, choose Update….
  • Which Mac needs what. The sound device goes on the Mac you work on. The iMac needs nothing extra: it plays through its own speakers. What you need