One speaker louder than the other on a Mac is two unrelated problems, searched with the same words. One has a free, built-in fix. The other has no free fix at all, because macOS was never built to offer one. Work out which you have before hunting for a setting that will not help.
Both get typed into Google exactly the same way: "one speaker is louder than the other." But whether that is a two-minute fix or a genuine gap in macOS depends entirely on whether you are listening to one physical device, or two separate devices playing together as a group. Below is how to tell which you have, the free fix for the first, and the honest answer for the second.
Is it one speaker, or two speakers grouped together?
Open System Settings, then Sound, then Output. If one device is selected, such as Built-in Speakers, MacBook Pro Speakers, or a single pair of headphones, you have Case A below: a stereo imbalance inside one piece of hardware. If instead the selected output is a Multi-Output Device, an aggregate output, or a Chorus group made up of two or more separate devices playing at once, such as two Studio Displays or two standalone speakers, you have Case B: two independent devices that are simply different volumes from each other.
Case A: one device sounds louder on one side
This is what macOS's own Balance control is for, and it is the complete fix. In System Settings, go to Sound, then Output, and select the device that sounds off-centre. A Balance slider appears beneath the volume control for any device with left and right channels, such as built-in speakers or headphones. Drag it toward the quieter side until the sound sits centred again. That one slider is the entire fix: nothing else needs installing, and there is no paid alternative to reach for.
If the sound still favours one side once the slider is centred, stop treating it as a software problem. Test the same audio through a second pair of headphones or a different speaker. If the imbalance follows the original hardware rather than the Mac, one driver is underperforming, or a cable or connector is faulty, and no setting on the Mac will correct that. A genuinely unbalanced pair of headphones is common enough to rule out before anything else.
Why doesn't the Balance slider fix two grouped speakers?
Because the Balance slider only ever balances left and right channels inside one device. It has no concept of "device A quieter than device B" across a group at all. Two Studio Displays, or two standalone speakers combined into a Multi-Output Device, rarely sit the exact same distance from where you actually listen, and different hardware puts out a different natural volume at the same setting even when it is sitting in the identical spot. Moving the Balance slider changes the stereo spread within each device; it does nothing to the gap between the two devices themselves.
Audio MIDI Setup does not help either. Every device you add to a Multi-Output Device plays at its own default level, with no per-device level control anywhere in that window. This is not a setting you have missed. It genuinely does not exist in macOS.
How do you fix two grouped speakers at different volumes?
With per-device balance inside the group itself, which is what Chorus's Groups feature is for. Combine your speakers into a Chorus group the same way you would build a Multi-Output Device, and each device inside that group carries its own relative level rather than macOS's single, all-or-nothing setting. Pull the closer speaker down to around 70% and leave the further one at 100%, and Chorus remembers that ratio every time you use the group, rather than resetting both to the same level the way macOS does.
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Download for MacWhat Chorus changes, and what it leaves alone
Chorus groups outputs using the same output-grouping mechanism already built into macOS, the one behind Audio MIDI Setup's Multi-Output Device. There is no kernel extension and no audio driver to install. The difference is what happens inside the group: one master volume for the whole group, plus a level for each device inside it that stays fixed relative to the others. The same group also gets one keyboard shortcut, follows your devices automatically when they reconnect, and responds to the Mac's volume keys with an on-screen readout, the same as a single device would.
It also leaves the thing macOS already does well alone. Chorus does not touch the Balance slider, because a single device's left and right balance is a system setting that already works, and a grouping app has no reason to duplicate it. Chorus does not add EQ, effects, or recording either; it groups, routes, and now balances devices against each other, and stops there.
For the step-by-step on building a Multi-Output Device, see Apple's own guide to Audio MIDI Setup.
Frequently asked questions
Does the Balance slider fix two separate speakers being different volumes?
No. The Balance slider only balances the left and right channels inside one stereo device, such as a pair of headphones or one speaker. It has no way to set one whole device quieter than another in a group, because macOS's Balance control was never built to compare devices, only channels within a single device.
Where is the Balance slider on a Mac?
In System Settings, go to Sound, then Output, and select the device that sounds unbalanced. A Balance slider appears beneath the volume control for any device that supports stereo channels, such as built-in speakers or headphones. Drag it toward the quieter side until the sound sits centred.
Why is one of my two grouped speakers quieter than the other?
Usually distance or hardware, not a fault. Two Studio Displays, or two standalone speakers, rarely sit the exact same distance from where you listen, and different hardware has a different natural output level even at the same volume setting. macOS has no per-device level control for a group, in Audio MIDI Setup or anywhere else, so the difference stays until something adjusts each device individually.
Can a faulty speaker or headphone cause one side to sound quieter?
Yes. Before assuming it is a settings problem, test the same audio through a different pair of headphones or a different speaker. If the imbalance follows the original hardware rather than the Mac, a driver has likely failed or a connector is faulty, and no software setting will fix it.
Does Chorus fix an unbalanced single speaker or pair of headphones?
No, and it is not meant to. A single device's left/right balance is handled by macOS's own Balance slider in System Settings, Sound, Output, which already does that job correctly. Chorus's per-device balance is for groups of two or more separate devices, where macOS has no equivalent control at all.
