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Halo On the Mac App Store · Free · macOS

One volume for all your speakers.

Halo un-greys the volume slider macOS disables on Multi-Output Devices.

The grey slider problem.

Run two Studio Displays, or any speakers-plus-headphones combination, through a Multi-Output Device and macOS gives up on volume. The menu-bar slider greys out, and the only way to change the level is one speaker at a time in Audio MIDI Setup.

Halo fixes it.

Halo is a small menu-bar app that writes the volume to every speaker in the aggregate at once, so they all move together. Drag its slider or scroll on its icon, and a proper HUD shows the level on the display you are using.

  • Scroll-wheel volume on the menu-bar icon, in 32 fine steps
  • A slider that works when Apple's is grey
  • A proper volume HUD on the display under your cursor
  • One-click Create Halo Speakers for two or more Studio Displays, drift-corrected so they never fall out of sync
  • Levels remembered across reboots
Halo's custom volume HUD shown over a macOS desktop
Halo's HUD, sitting where Apple's used to.

What Halo needs.

macOS 13 or later, on Apple silicon or Intel. Two or more Studio Displays for the one-click setup; any other Multi-Output Device works once you have created it in Audio MIDI Setup.

The App Store version does not ask for accessibility access, so the keyboard's volume keys stay with macOS. Use Halo's slider or the scroll wheel instead.

Nothing leaves your Mac.

Halo has no account, no analytics and no network access. It is sandboxed and talks only to CoreAudio. Your volume levels stay in the app's own preferences on your Mac. Read the privacy policy.

Questions

Why is the volume greyed out on my Mac?

Because a Multi-Output Device is selected as the output. macOS does not control the volume of an aggregate device, so it greys out the slider. Halo writes the level to each speaker inside the aggregate instead.

Does Halo work with two Studio Displays?

Yes. That is what it was built for. Create Halo Speakers joins them into one output with one volume and keeps their clocks in sync so the audio never drifts apart.

Does Halo use the keyboard volume keys?

The App Store version does not. Controlling those keys needs an accessibility permission that the App Store version does not ask for, so you change the volume with Halo's slider or by scrolling on its menu-bar icon.

Is Halo free?

Yes. Halo is free on the Mac App Store.

Download on the Mac App Store Free · macOS 13 or later · Apple silicon & Intel

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