Multi-Output Device Mac — How to Create One in Audio MIDI Setup

What Is a Multi-Output Device on Mac?

A multi-output device is a virtual audio device created in macOS Audio MIDI Setup that combines two or more audio outputs into a single device. When an application sends audio to the multi-output device, the audio plays through all included outputs simultaneously. This is how custom soundboard apps route audio to both headphones and a virtual audio driver at the same time.

The most common use case combines headphones (for personal monitoring) with BlackHole (for routing to OBS, Discord, or Zoom). The user hears the soundboard through headphones while streaming software or voice chat receives the same audio through the virtual driver.

How Do You Create a Multi-Output Device?

Open Audio MIDI Setup from Applications, then Utilities. Click the plus button in the bottom left. Select "Create Multi-Output Device." Check the boxes for your headphones or speakers and for BlackHole 2ch. Set headphones as the master clock device. Rename the device to something descriptive.

Open Audio MIDI Setup Applications > Utilities > Audio MIDI Setup
Click the plus button, select "Create Multi-Output Device" bottom left corner
Check headphones/speakers and BlackHole 2ch both devices in the group
Set headphones as the master clock device physical device controls timing
Enable Drift Correction on BlackHole compensates for clock differences
Rename the device e.g. "LitPads + Headphones"

The master clock device determines the sample rate and timing for all outputs in the group. Set this to your headphones or speakers (the physical device) rather than BlackHole. Enable "Drift Correction" on BlackHole to prevent audio artifacts caused by clock differences between devices.

The BlackHole audio setup on Mac covers the complete workflow from installing BlackHole to creating the multi-output device to configuring the receiving application.

How Do You Use the Multi-Output Device with LitPads?

Set the multi-output device as the system audio output in macOS System Settings under Sound. LitPads outputs to whatever device macOS uses as the default output. All pad audio then flows to both headphones and BlackHole simultaneously without any LitPads-specific configuration.

LitPads does not have its own audio output selector. The app uses the system default output device. This simplifies setup: change the system output once and LitPads follows automatically. The same approach works for any best soundboard for streaming.

What Are Common Multi-Output Device Issues?

The most common issues are sample rate mismatches (causing clicks and pops), missing drift correction on BlackHole (causing gradual audio desync), and the multi-output device not appearing in System Settings (requires closing and reopening Audio MIDI Setup or restarting).

Sample rate: open Audio MIDI Setup, select the multi-output device, and ensure all sub-devices use the same sample rate (44,100 Hz or 48,000 Hz). Mismatched rates cause audible artifacts.

Drift correction: enable it on BlackHole within the multi-output device settings. BlackHole runs on its own clock, which may drift slightly from the physical audio device. Drift correction compensates automatically.

The audio routing on Mac covers additional edge cases including USB audio interface compatibility and Bluetooth headphone limitations with multi-output devices.

Can You Control Volume Per Output in a Multi-Output Device?

macOS does not expose individual volume controls for sub-devices within a multi-output device. The system volume slider controls the master output level for all sub-devices equally. Volume adjustments for individual outputs must be made in Audio MIDI Setup or through the individual device's own controls.

Adjust volume balance using OBS's audio mixer, Discord's input sensitivity, or LitPads' per-pad volume controls rather than the system volume slider.

This limitation means the soundboard audio level in OBS or Discord is the same as what you hear through headphones. Adjust the balance using OBS's audio mixer (lower the BlackHole source volume) or Discord's input sensitivity slider rather than the system volume.

LitPads provides per-pad volume controls and a master volume that affect the output level before it reaches the multi-output device. Adjust individual pad volumes within LitPads to fine-tune the balance between different sounds in the stream.

Marcel Iseli

Indie Developer · DJ · Producer

Marcel Iseli is an indie developer, DJ, and music producer with over 20 years behind the decks and in the studio. Rooted in hip hop culture, he collects drum machines, samplers, and vintage audio gear. LitPads grew out of that obsession: decades of triggering samples on hardware led him to build the software equivalent he always wanted.