Audio MIDI Setup is a utility built into every Mac, sitting quietly in Applications > Utilities. It is not a music production tool. It is the control panel for Core Audio, the part of macOS that manages every speaker, microphone and audio interface connected to your Mac, and it is where a Multi-Output Device or an Aggregate Device actually gets built.
Most people never open it, because most people never need to. It surfaces the moment something audio-related gets slightly unusual: two speakers that should play together, a microphone macOS is not detecting properly, a sample rate mismatch causing a crackle. When that happens, Audio MIDI Setup is the tool Apple expects you to reach for, and it has been sitting there, unopened, the entire time.
Why the name is confusing
The name suggests MIDI keyboards, synthesisers, and music production software, which is a reasonable thing to assume and mostly wrong. Audio MIDI Setup does have a MIDI Studio tab, for configuring MIDI hardware and virtual MIDI ports, but it is a secondary feature bolted onto an app that is really about something else: managing ordinary audio devices, the speakers and microphones every Mac already has, whether or not you own a single piece of music gear.
What Audio MIDI Setup actually shows you
Open it and the left-hand column lists every audio device macOS currently knows about: built-in speakers and microphone, any USB or Bluetooth device connected, and any combined devices you have already built. Select one and the right-hand panel shows its input and output channels, its current sample rate, and a set of source and gain controls that vary depending on the hardware.
The sample rate matters more than it looks. Every audio device runs its own internal clock, and when two devices are meant to work together at different rates, you get crackling, dropouts, or audio that drifts slowly out of sync. Audio MIDI Setup is where you check what rate a device is actually running at, and where you set it to match another device it needs to work alongside.
Building a Multi-Output or Aggregate Device by hand
The + button in the bottom-left corner of the device list is where the two combined device types get built. A Multi-Output Device fans one audio stream out to several speakers so they all play the same thing at once, which is what most people are after when they want two speakers to work together. An Aggregate Device does the reverse, combining several microphones or interfaces into one device with more input channels, mainly used for recording several sources at once. The two are named almost identically and solve different problems; the full breakdown is in our guide to what separates them.
Both are built the same way: tick the devices you want in the checklist, give the result a name if you care to, and it appears in the Sound menu like any other device from that point on. It works. It is also entirely manual, and that is where the honest limitations start.
Where it runs out
Audio MIDI Setup was built to expose the underlying mechanism, not to make living with it pleasant day to day, and four gaps show up quickly once you use a combined device regularly.
- No memory. There are no named presets and no saved arrangements. Whatever you build stays in the device list, but there is no way to keep several different setups ready and switch between them.
- No working volume for the combined device. A Multi-Output Device is not a real device with its own volume, so the slider and your volume keys have nothing to control. Each real device inside it has to be adjusted on its own Master slider, individually.
- No fast way to switch. Reaching a combined device again means opening Audio MIDI Setup, finding it in the list, and selecting it in the Sound menu. There is no shortcut, no menu-bar access, nothing quicker than the same route every time.
- A genuinely confusing interface. Small icons, unlabelled controls, and a layout built for people who already understand Core Audio. For anyone who does not, it is not obvious what half of the checkboxes and dropdowns actually do.
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None of this makes Audio MIDI Setup a bad tool. It is the real mechanism, built into every Mac, and it is not a stripped-down demo of anything, it is the actual technology. Chorus itself sits directly on top of it: Groups use the same output-grouping macOS provides through Audio MIDI Setup, not a different or proprietary one. There is no driver, no kernel extension, nothing added to your Mac that was not already there.
What changes is what is built around that mechanism. Chorus adds a real working volume for a group, with per-device balance so a quieter speaker can be brought up to meet a louder one. Per-App Audio sends a call through your headphones while everything else plays through the room, something Audio MIDI Setup has no way to do at all. Auto-Switch follows your devices as they connect and disconnect, so a group survives unplugging a display without a trip back into Utilities. Keyboard Shortcuts and Volume Keys & HUD put the whole thing a keypress away, and Automation reaches it from Raycast, Shortcuts or a Stream Deck. The full case for paying for that layer, versus sticking with the free route, is in our comparison against Audio MIDI Setup.
What Chorus does not do is worth saying plainly: no EQ, no audio effects, no recording or capture, no DAW-style routing between apps. For that, Audio MIDI Setup and the MIDI Studio tab it is named after remain the right place to look.
For the step-by-step on building a Multi-Output Device, see Apple's own guide to Audio MIDI Setup.
Frequently asked questions
What is Audio MIDI Setup used for?
Audio MIDI Setup is the built-in Mac utility for managing audio devices at a system level. It lists every connected input and output, lets you check and set each device's sample rate, and is where you build a Multi-Output Device to combine speakers or an Aggregate Device to combine microphones.
Does Audio MIDI Setup have anything to do with MIDI keyboards or music production?
Barely. Despite the name, Audio MIDI Setup is mainly a control panel for Core Audio, the part of macOS that manages speakers and microphones. MIDI device management exists as a separate tab within the same app, but it is a small part of what the utility actually does.
Where do I find Audio MIDI Setup on a Mac?
Open Finder, go to Applications, then Utilities, and Audio MIDI Setup is in that folder. You can also open it by searching for its name in Spotlight.
Can Audio MIDI Setup save more than one device combination?
No. Whatever Multi-Output or Aggregate Devices you build stay in the device list permanently, but Audio MIDI Setup has no concept of named presets or saved arrangements to switch between. Every different setup has to be built, renamed, or reselected by hand.
Does Chorus replace Audio MIDI Setup?
No, it builds on it. Chorus groups outputs using the same mechanism Audio MIDI Setup exposes manually, then adds a working volume for the group, per-app routing, automatic switching and keyboard shortcuts, the parts the built-in utility leaves for you to handle yourself.
