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How to play sound through two outputs at once on a Mac

Updated

A Mac can play the same sound through several outputs at once, for example the built-in speakers and a pair of headphones. The setting is hidden in Audio MIDI Setup, where you combine the outputs into a Multi-Output Device.

Create a Multi-Output Device

  1. Open Audio MIDI Setup. It is in Applications → Utilities, or you can find it with Spotlight.
  2. Click the + button at the bottom left and choose Create Multi-Output Device.
  3. Tick Use next to each output you want, for example MacBook Pro Speakers and your headphones.
  4. Set Primary Device to the wired or built-in output, and turn on Drift Correction for the others.
  5. Open System Settings → Sound and choose the new Multi-Output Device under Output.

To give the device a clearer name, double-click it in the sidebar of Audio MIDI Setup.

What to expect

The volume keys stop working

macOS cannot change the volume of a Multi-Output Device with the keyboard or Control Center. Set the volume of each output before you switch to the combined device, or change it later in Audio MIDI Setup.

Bluetooth plays late

Bluetooth headphones and speakers usually play somewhere between 100 and 300 milliseconds behind wired outputs, and macOS does not line them up. Drift Correction keeps the clocks together but leaves this delay in place. If you can hear both at once, it sounds like an echo. When two people listen in different places, the delay is rarely a problem.

A TV can be late too

A TV connected over HDMI processes sound before it plays it, and macOS often doesn’t know how long that takes. In our test a TV played about 100 ms later than macOS reported, which is enough for a clear echo next to the Mac’s speakers.

AirPlay plays later still

AirPlay speakers buffer about two seconds of audio, so they drift far apart from local outputs. To play music on several AirPlay speakers in sync with each other, use the AirPlay button in the Music app instead.

Silence or crackling on one device

Open Audio MIDI Setup and give every device in the group the same sample rate, usually 48,000 Hz. Drift Correction should be on for every device except the primary one.

Go back to one output

Choose your usual output again in System Settings → Sound. To delete the combined device, select it in Audio MIDI Setup and click the − button.

To hear several outputs in one room without an echo, the faster devices have to wait for the slowest one. Levels 1.4 does that from the menu bar, without a Multi-Output Device. See how to play audio on multiple outputs in sync.