Virtual audio devices can be used as simple pass-thru devices, but Loopback provides much more power by allowing you to configure audio from specific sources to flow through a device. This is done in the Sources column of the Device Editor.

The Sources column in its default state

When a device is created, it will contain only the special Pass-Thru source. This allows audio to enter the device as input and be passed out as output, which allows audio to be piped directly between applications without any further configuration needed in Loopback. For more details on Pass-Thru, see the Notes on Pass-Thru page.

For more control, you can configure your virtual audio device to pull in audio from specific audio sources (both applications and physical devices). To add a source to a device, click the (+) button at the top of the Sources column, then select an application or audio device. Any audio produced by the source will then be included in the virtual audio device’s output.

Below, you can see that we've added the software application Music to our device, as well as a USB microphone.

The Sources column, with audio sources added

Thanks to Loopback, the audio from all these sources will be combined into one virtual device.

Additional Settings

On/Off Toggle

The “Music” source is on, while the “USB Mic” source is off

Using the On/Off switch, you can toggle an individual audio source off. This enables you to temporarily exclude the source's audio from the virtual device without deleting the source and losing its configuration.

Volume Sliders

A source's volume slider

All source types (Applications, Audio Devices, and Pass-Thru) offer a volume slider under the Options area. In general, leaving these at their default 100% level is best. If desired, you can use these sliders to adjust the relative level of audio provided by the source, as it compares to other sources in the virtual device.

A source's volume slider while muted

The speaker indicator to the left of the volume slider can act as a mute switch. Click it to mute the source, without affecting the volume setting. This can be used to temporarily prevent the source's audio from being included in your device.

Mute checkbox

An application's “Mute when capturing” checkbox

Application sources feature a second setting in their Options area: the Mute when capturing checkbox. This checkbox is on by default, which means that when the virtual audio device is in use, audio from the application source will not be played through. This is usually desirable, as applications using the Loopback virtual audio device will frequently want to perform their own audio play-through, after some amount of processing.

In most cases, you'll want to leave this checkbox in its default On state. However, if you want the audio from an application source to be audible regardless of how the virtual device is being used, you can toggle the checkbox off.

Removing a Source

To remove an audio source from your virtual device, click on it in the editor to highlight it, then click the Delete button in the bottom bar or select Delete from the Edit menu.

Channel Mapping

By default, Loopback maps sources to output channels automatically. For details on adjusting this mapping, read over the Output Channels page.

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