What is a Multi-Output Device in MacOS?
Multi-Output Devices are very handy in MacOS. They allow you to output audio to multiple audio devices at the same time. For example, you can send audio data to speakers and headphones at the same time. The most common use case is to use a multi-output device to record the system audio on MacOS.
However, multi-output devices come with a big downfall: you cannot adjust the volume on your Mac while using one. If you attempt to change the volume via the keyboard, a cancelled volume image will appear. The touch bar and menu bar volume controls will also be grayed out.
Why Does Apple Prevent you From Changing the Volume with a Multi-Output Device?
The main reason Apple blocks you from changing the volume while using a multi-output device is because they don’t know which audio device you want to change the volume for. Since the audio is going to multiple outputs, we need to manually select the device we want to change.
How to Adjust the Volume
Adjust the Volume in Audio Midi Setup
To change the volume, open Audio Midi Setup and select the audio device that is actually producing the sound. For example, the audio might be coming out of your MacBook Pro Speakers. After selecting this, you can then change the audio level using the Master knob and it will bypass the restriction on volume control.
Pro tip: The easiest way to open Audio Midi Setup is to press CMD + Spacebar to bring up spotlight and type “Audio Midi Setup”. The app will come up and you can hit enter to open it. It’s a bit tedious to open the program any other way, so this can help you speed up the process.
MacOS Programs That Offer Volume Control
Now, you’ve got the gritty way to adjust the volume while using a multi-output device, so let’s get to the fun stuff! There are a few developers out there that saw this annoying problem and wanted to fix it. Showcased here is a free option and a paid option to help fix our problem.
Adjust the Volume with MultiSoundChanger [Free]
MultiSoundChanger is an awesome free app developed by Dmitry Meduho and can found here on Github. This app will let you change the volume, even when you are using a multi-output device. It also has a very native MacOS feel as it looks nearly identical to the original volume controller on MacOS.
The way MultiSoundChanger works is by targeting the Master volume control programmatically, so you can adjust it via the menu bar.
This is the optimal way to change the volume, however the program does come with a downside. While adjusting the volume, it will adjust all audio devices that are part of the multi-output device. This means if you want to have individual volume control for each device, it’s probably not the best option for you.
Adjust the Volume with Loopback [Paid]
Loopback is a fantastic program created by Rogue Amoeba that allows you to route audio in a variety of ways and truly gives you the audio freedom a hardcore user would want. In fact, Loopback allows you to route audio to multiple outputs without even needing a multi-output device.
This takes away all the complications created by a multi-output device. Although it is pricey, for a serious audio user on MacOS this program is definitely worth it if you can make use of all its features.
To wrap this up, MacOS makes it difficult to adjust the volume levels when using a multi-output device. Luckily, we have some great options out there that are both free and paid to help solve these problems.
Similar to MultiSoundChanger, my own personal app AVTouchBar (an audio visualizer for the Touch Bar) will bypass the MacOS volume restriction by programmatically changing the volume inside Audio Midi Setup with a custom Touch Bar gesture. It will target specifically the audio device that is creating the sound so there is no downside to doing it this way.
Here’s a video if you want to check out the app!
Jake is a professional baseball player that was drafted by the Toronto Blue Jays in 2016. He played in the minor leagues for the Blue Jays for 5 years until he was drafted by the Miami Marlins in the rule 5 draft in 2020. In his spare time, he enjoys creating technology videos on YouTube and pursuing creative technologies including an audio visualizer for the touch bar on MacBook Pros.