Recording Mac System Audio with BlackHole

macOS lets recording software read a microphone directly, but it does not provide a general-purpose “system audio” input. When Safari is playing a video, for example, QuickTime Player or a DAW can usually see the microphone but cannot use Safari’s audio as a recording source.

BlackHole is a virtual audio loopback driver. It makes the audio sent by one application available as an input that another application can read. This guide first builds a mental model of inputs and outputs, then walks through two common setups:

recording system audio without monitoring it;
recording system audio while listening through speakers or headphones.

It also explains how to use an Aggregate Device to make system audio and a microphone available to recording software at the same time.

1. Concepts and Preparation

1.1 Input and Output Are Relative to the Mac

In Audio MIDI Setup:

Input means audio entering the Mac, such as a microphone feeding recording software.
Output means audio leaving the Mac, such as Music sending sound to headphones.

Labels such as 1 in / 0 outs and 0 ins / 2 outs describe the number of channels, not the number of devices. A mono microphone usually has one input channel, while a stereo playback device normally has two output channels: left and right.

One device can also have both inputs and outputs. A USB audio interface, for example, can send a microphone into the Mac and send Mac audio to headphones. When deciding whether something is an input or output, ask where the signal is traveling instead of assigning a permanent role to the device.

1.2 BlackHole Is a Virtual Audio Cable

A normal playback path looks like this:

After changing the system output to BlackHole, the path becomes:

BlackHole is an output destination from the playback application’s perspective and an input source from the recorder’s perspective. That is why it appears in both input and output device lists.

BlackHole has no physical speaker. If you send system output directly to it, recording software receives the signal but you cannot hear it. To record and monitor simultaneously, create a Multi-Output Device.

1.3 Choose the Right Setup

Goal	macOS output	Recording software input	Other devices
Record system audio only	BlackHole 2ch	BlackHole 2ch	None
Record and monitor system audio	Multi-Output Device	BlackHole 2ch	Speakers/headphones + BlackHole
Record system audio and microphone separately	Multi-Output Device	Aggregate Device	BlackHole + microphone

The first two setups cover most screen recordings, podcast material, and demo videos. You need an Aggregate Device only when the recording software cannot select multiple input devices independently.

1.4 Install BlackHole 2ch

BlackHole 2ch is sufficient for ordinary stereo system-audio recording. If Homebrew is installed, run:

brew install blackhole-2ch

You can also download the installer from the BlackHole website. Close applications that are using audio before installation, and restart the Mac if the installer asks you to.

After logging back in, open:

Applications → Utilities → Audio MIDI Setup

You can also press Command + Space and search for Audio MIDI Setup. BlackHole 2ch should appear in the left side of the Audio Devices window. If that window is not visible, choose Window → Show Audio Devices.

BlackHole 16ch and 64ch suit workflows that require many channels. For ordinary desktop recording, 2ch is easier to configure and preserves stereo audio.

2. Record System Audio

2.1 Record BlackHole Directly

If you do not need to hear system audio while recording, use BlackHole directly:

Open System Settings → Sound → Output.
Select BlackHole 2ch.
Set the input device in the recording software to BlackHole 2ch.
If the software asks for channels, select channels 1–2 in stereo.
Play some audio and check that the recorder’s level meter moves before starting the recording.

Every application using the default system output now sends audio to BlackHole rather than the physical speakers. When recording is complete, switch the macOS output back to MacBook Speakers, your headphones, or the audio interface you normally use.

Some applications read the audio-device configuration only when they start. If there is still no signal after switching the system output, quit and reopen the playback and recording applications.

2.2 Monitor While Recording

A Multi-Output Device sends the same signal to several outputs: one copy goes to the speakers or headphones, while another goes to BlackHole.

Open Audio MIDI Setup.
Click the + button in the lower-left corner and choose Create Multi-Output Device.
Rename the new device, for example to Recording Output.
In the right pane, enable a physical playback device such as MacBook Speakers or wired headphones.
Enable BlackHole 2ch as well.

Set the physical playback device as the Primary Device or Clock Source and keep it at the top of the list. BlackHole’s documentation specifically recommends using Built-in Output or another two-channel playback device as the primary device. If BlackHole appears first, disable and re-enable its Use checkbox to reorder it.

2.3 Set the Sample Rate and Drift Correction

The devices in a Multi-Output Device have independent clocks and may drift apart over time. Check that:

every device uses the same sample rate, such as 44.1 kHz or 48 kHz;
the physical playback device is the Primary Device or Clock Source;
Drift Correction is enabled for BlackHole and every other device that is not the clock source.

You do not have to choose one particular sample rate, but the devices and project in the same recording path should match. If pops, dropouts, or speed changes begin after recording for a while, check these settings first.

2.4 Switch macOS and the Recording Software

After creating the device:

Select Recording Output in System Settings → Sound → Output. Alternatively, Control-click it in Audio MIDI Setup and choose Use This Device For Sound Output.
Select BlackHole 2ch as the input in the recording software.
Play a test sound and confirm that you can hear it and that the recorder’s level meter responds.

Do not set the recording software’s input to the Multi-Output Device. That device sends audio to the speakers and BlackHole; BlackHole remains the device from which the recorder reads audio.

2.5 Multi-Output Volume Limitations

macOS does not support changing the overall volume of a Multi-Output Device with the system volume keys. Disabled keyboard volume keys are expected and do not indicate a configuration problem.

To change monitoring volume, use one of the following:

the physical volume control on the headphones, speakers, or audio interface;
the control for an individual playback device in Audio MIDI Setup;
the volume control in the playback application.

Watch the recording level in the source application or recorder to avoid clipping. Lowering the physical speaker’s monitoring volume does not necessarily change the signal level sent to BlackHole.

2.6 Test with QuickTime Player

QuickTime Player provides a quick way to verify the route:

Choose File → New Audio Recording.
From the menu beside the recording controls, choose BlackHole 2ch as the microphone or input source.
Play audio in a browser or Music.
Confirm that the level meter responds, then start recording.

If the macOS output is the Multi-Output Device, you can continue monitoring through the selected speakers or headphones while recording.

2.7 A DAW, Audacity, or OBS

The labels vary between applications, but the essential settings are the same:

Audio input/device: BlackHole 2ch
Channels: 1–2
Mode: Stereo

Some newer recording and streaming applications can capture audio from an individual application directly. If your software supports that feature, BlackHole may be unnecessary. BlackHole remains useful for routing audio across applications or DAWs and for software that uses standard Core Audio devices.

On first use, macOS may ask the recording application for Microphone permission. Applications can require this privacy permission to access audio inputs even when the source is a virtual device. If the level meter never moves, check System Settings → Privacy & Security → Microphone.

3. Record System Audio and a Microphone Together

A Multi-Output Device and an Aggregate Device solve different problems:

A Multi-Output Device sends one signal to several outputs.
An Aggregate Device combines several audio devices into one larger device.

If the recorder accepts only one input device and you need both BlackHole and a microphone, create an Aggregate Device:

Click the + button in the lower-left corner of Audio MIDI Setup.
Choose Create Aggregate Device.
Enable BlackHole 2ch and the microphone you want to use.
Set every subdevice to the same sample rate.
Choose a reliable Clock Source and enable Drift Correction for the other devices that are not synchronized in hardware.
Choose this Aggregate Device as the input in the recording software.

The complete signal path looks like this:

An Aggregate Device collects channels; it does not automatically mix them to stereo. The recorder may show BlackHole as channels 1–2 followed by the microphone channels. Refer to the channel order shown in Audio MIDI Setup and assign system audio and microphone to separate tracks so you can adjust their levels independently in post-production.

If the software already lets each track use a different device, or it can capture system audio and a microphone natively, you do not need an Aggregate Device for this purpose.

4. Troubleshooting and Cleanup

4.1 Nothing Is Recorded

Check each part of the route in order:

The macOS output is BlackHole 2ch or a Multi-Output Device that contains BlackHole.
The recorder’s input is BlackHole 2ch or an Aggregate Device that contains it.
The playback application uses the system default output instead of another explicitly selected device.
BlackHole channels 1–2 are not muted and their volume is not zero.
The recording application has macOS Microphone permission.
Applications that retained the old route have been reopened after changing devices.

4.2 Recording Works, but You Cannot Hear Anything

The system output is probably set directly to BlackHole 2ch. To monitor it, create a Multi-Output Device containing BlackHole and a physical playback device, then select that Multi-Output Device as the macOS output.

4.3 You Can Hear Audio, but the Recording Is Silent

Verify that the Multi-Output Device includes BlackHole 2ch and that the recorder is reading BlackHole rather than the speakers. Some applications do not show a signal until a track has been created or armed for recording.

4.4 Playback Stops, or Pops Appear After a While

Make Built-in Output or another two-channel playback device the primary or clock device and keep it at the top of the Multi-Output list. Then verify that the sample rates match and that Drift Correction is enabled for devices other than the clock source.

Bluetooth headphones can change their channel configuration or sample rate when switching into microphone mode, which can destabilize the route. Test with the built-in speakers or wired headphones first to remove Bluetooth from the troubleshooting path.

4.5 The Keyboard Volume Keys Do Not Work

This is a macOS limitation of Multi-Output Devices. Adjust an individual physical device, the application volume, or a hardware volume knob instead.

4.6 You Hear an Echo or Loud Feedback

Do not send the monitored output of the recording software back into the same BlackHole route, or it will form a loop:

Disable software monitoring for that track, or route monitoring only to a physical device that does not feed BlackHole. When using a microphone, headphones also prevent speaker audio from being picked up by the microphone again.

4.7 Restore the Normal Output After Recording

When recording is finished, select your usual speakers, headphones, or audio interface again in System Settings → Sound → Output. You can keep the Multi-Output and Aggregate Devices for next time, or select them in Audio MIDI Setup and click − to remove them.

The entire workflow can be reduced to three statements:

The playback application sends its output to BlackHole.
The recording software reads its input from BlackHole.
To monitor at the same time, add a Multi-Output Device on the output side.

If you follow the signal and ask who is producing output, where that output goes, and who is reading the input, configuring BlackHole becomes a route that can be verified one segment at a time rather than a series of guesses about device names.