FIX: Cannot Adjust Volume on a Mac OS X with External Devices

Using external speakers, USB DACs, or HDMI/DisplayPort audio devices on a Mac often makes the volume buttons stop working, and the system volume slider appears grayed out in Sound settings. This is because macOS expects these devices to control the audio volume themselves. 

Most of the time, these external devices do not let macOS adjust their volume. Changes in how Mac handles audio, especially in newer versions, can also cause this issue. Now that you know the causes, let’s discuss the solutions.

1. Kill the coreaudiod Process

1. Go to Finder -> Applications -> Utilities -> Terminal. Open the Terminal app.
2. In Terminal, type the following command and then enter your password:

   sudo killall coreaudiod

3. The password field will look empty as you type—this is normal. Just type your password and hit Enter.
4. After running this command, try adjusting the volume again to see if the problem is fixed.

Workaround: Adjust Volume Using Terminal

As an alternative, you can set the volume through Terminal. While this method isn’t as convenient, it can come in handy for troubleshooting.

Just enter the following command, changing the number (5) to set the desired volume level:

sudo osascript -e “set Volume 5”

2. Disconnect and Reconnect Audio Device

If this issue pops up when you don’t have any external audio device connected, a simple trick is to plug in a pair of headphones or speakers and then unplug them. Sometimes, this can reset your Mac’s audio settings.

3. Select the Correct Audio Output

To help explain things, let’s look at a typical situation: let’s say you have a Sharp TV connected to your Mac via HDMI. If you can’t adjust the volume with the keyboard and the speaker icon looks disabled.

1. Click the Apple icon in the top left, and go to System Preferences -> Sound -> Output.
2. If your sound output is set to your SHARP LCD (via HDMI), adjusting the Mac’s volume won’t work—you’ll need to change the volume using the TV’s controls. On the other hand, if Internal Speakers are selected as the output, you’ll be able to control the volume from your Mac as usual.

4. If Your External Device Does Not Support Volume Control

If your external device doesn’t support volume control, you can use a free tool called SoundFlower. SoundFlower lets audio flow between different applications and devices, so you can adjust volume even when it’s otherwise locked.

1. Download and install SoundFlower from here.
2. Next, open Audio MIDI Setup from Applications -> Utilities -> Audio MIDI Setup.
3. Click the + (plus sign) at the bottom left of the window and choose Create Multi-Output Device from the menu.
4. On the right pane, check the boxes for SoundFlower (2ch) and your external device, or Internal Speakers if you don’t have an external device connected.
5. Then, right-click (or Control + Click) on Create Multi-Output Device, and select Use This Device for Sound Output from the menu.