How to Create and Configure Virtual Audio Routing on Mac Using BlackHole and Audio MIDI Setup

Podcasters, live streamers, remote instructors, and musicians frequently need to capture internal computer audio on macOS. Whether you want to stream background music from Spotify into Discord, record meeting audio from Zoom inside Audacity, or send DAW tracks to OBS Studio, macOS intentionally prevents applications from recording system audio directly due to sandboxing and copyright protections. The open-source BlackHole virtual audio driver solves this limitation by creating virtual loopback pathways. When combined with macOS Audio MIDI Setup, BlackHole enables users to route audio between applications seamlessly without physical cables or audio degradation.

Understanding BlackHole Virtual Audio Driver Architecture

BlackHole operates as an in-memory Core Audio driver that functions simultaneously as a virtual audio output and a virtual audio input:

• Virtual Loopback: Any audio transmitted into the BlackHole output device is immediately mirrored to the BlackHole input device with zero latency and zero digital loss.
• Multi-Output Device: Because standard macOS audio only routes to a single output, creating a Multi-Output Device allows sound to play simultaneously through your physical headphones and the virtual BlackHole driver.
• Channel Flavours: BlackHole is available in 2-channel, 16-channel, and 64-channel variants depending on how many isolated audio streams you require.

Installing BlackHole on macOS

Install the driver using the Homebrew package manager or the official installer package:

Option 1: Installing via Homebrew

1. Open Terminal on your Mac.
2. To install the standard 2-channel version, execute:

   brew install blackhole-2ch

3. If you manage multi-track recording in DAWs, install the 16-channel version:

   brew install blackhole-16ch

Option 2: Installing via Direct Installer

1. Download the .pkg installer from the official ExistentialAudio GitHub repository.
2. Run the installer and enter your macOS administrator password when prompted.
3. Restart your Mac or restart the Core Audio daemon via Terminal:

   sudo killall coreaudiod

Creating a Multi-Output Device in Audio MIDI Setup

If you set your Mac system output exclusively to BlackHole, you will not hear any audio through your physical speakers or headphones. Creating a Multi-Output Device solves this by splitting the audio stream.

Step 1: Accessing Audio MIDI Setup

1. Press Cmd + Spacebar, search for Audio MIDI Setup, and press Enter.
2. Click the + (Plus) icon in the lower-left corner of the Audio Devices window.
3. Select Create Multi-Output Device.

Step 2: Selecting Output Hardware

1. In the right-hand panel, check the box adjacent to your primary physical listening device (e.g. External Headphones or MacBook Pro Speakers).
2. Check the box adjacent to BlackHole 2ch.
3. Under the Master Device dropdown, ensure your physical headphones or speakers are designated as the master clock source.
4. Check the Drift Correction box next to BlackHole 2ch to prevent audio sync drift over long recording sessions.

Routing Application Audio for Recording and Streaming

Now configure your operating system and target software to complete the pipeline:

Step 1: Assigning System Sound

1. Open System Settings > Sound > Output.
2. Select your newly created Multi-Output Device as the primary system output. All computer audio will now play through your headphones and feed into BlackHole simultaneously.

Step 2: Capturing the Stream in OBS Studio, Audacity, or Zoom

1. Open your recording application (e.g. Audacity, Logic Pro, or OBS Studio).
2. Navigate to Audio Settings / Sources.
3. Set the Input Device (Mic/Aux) to BlackHole 2ch.
4. Play audio on your Mac (such as a YouTube video or browser track). The audio meter inside your recording software will register live audio levels, confirming successful internal routing.

Tuning Sample Rates to Eliminate Clicks and Pops

If you encounter digital distortion, crackling, or latency:

• Open Audio MIDI Setup.
• Select both your physical listening device and BlackHole 2ch.
• Ensure both devices are set to the identical Format sample rate (e.g., both set to 48,000 Hz or both set to 44,100 Hz). Mismatched sample rates are the primary source of buffer jitter in Core Audio.

Utilising BlackHole alongside macOS Audio MIDI Setup provides professional, studio-grade audio routing across macOS without third-party subscriptions or hardware splitters.