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When connected to a Mac, many audio output devices fail to provide proper volume adjustment. Displays connected via HDMI or DisplayPort, as well as many other non-standard digital devices, simply offer no output controls. As a result, MacOS won’t let you adjust the volume level for these devices, and the volume keys on your keyboard won’t have any effect.
SoundSource works behind the scenes to provide volume adjustments for all audio devices, and makes it possible to control the volume levels for any audio output—even those that don’t allow it by default.
When SoundSource is running, it can adjust volume for any output in its main window. The volume slider adjusts the levels heard through the selected output device.
Even devices that normally don’t offer volume controls will work from the main window. If you set one of these devices as your system output, use the volume slider to adjust its volume.
Audio devices without volume controls show a warning when using the keyboard keys. This overlay indicates the volume level won’t change:
SoundSource’s Super Volume Keys feature can remove this limitation. Enabling Super Volume Keys, in SoundSource’s preferences, extends its volume-change capabilities to your keyboard.
To turn on Super Volume Keys, open SoundSource’s Preferences window. In the Audio tab, enable the Super Volume Keys checkbox. Your keyboard volume keys will then be able to adjust any audio device you set as the System Output.
In rare cases, some audio devices report volume controls to MacOS but won’t respond to adjustments. This unusual audio hardware keeps SoundSource from the functionality you expect. Even Super Volume Keys won’t help on its own.
An option to Force software volume control gives SoundSource special software-based volume controls. Make sure to select the appropriate device, in the Hidden Preferences of SoundSource’s Debugging window, and you’ll be set.
To access that setting, we’ll re-launch SoundSource. Start by clicking on the Options (Gear) menu in SoundSource’s main window, and navigate to the Help menu. Holding down the Option key on your keyboard replaces the Contact Us command with Quit and Relaunch for Debugging.
Selecting that will quit SoundSource, and relaunch it to its Debugging window. In the Hidden Preferences section, the Force software volume control option uses a pop-up button in the Value column. Click that to reveal a list of all output devices. Only select the device which needs forced software volume controls, otherwise you may end up with unexpected results.
Once that’s set, click the Done button to finish launching SoundSource. It will run with that tweak enabled, so you can adjust volume as expected.
When SoundSource is running, it should provide full volume control for all your audio output devices. When you need to, enabling Super Volume Keys and forced volume controls can expand its abilities to use your keyboard’s volume keys with any device. So if you play audio through a hardware device that does not ordinarily provide volume control, SoundSource stands ready to assist.