You press the volume key, the bar is already full, and the dialogue in the video is still too quiet. This happens on every Mac, and it is not a defect. It is the point where the output stage runs out of headroom.
Understanding where that ceiling comes from is what separates a fix that works from one that turns your audio into a distorted mess.
Why the slider stops where it stops
The macOS volume slider is an attenuator. At 100% it is not amplifying anything, it is simply not reducing the signal at all. Everything below full volume is subtraction. There is nothing above it to give you, because the system never adds gain of its own.
So when a track is mastered quietly, or a video was recorded with the microphone too far away, the ceiling you hit is the file’s, not your Mac’s. Getting more level means adding gain somewhere after the application and before the speakers.
What actually raises the ceiling
There are three real options, in ascending order of how much they help.
Raise the volume inside the application. Many apps have their own volume control that multiplies the system volume. Music, QuickTime and most browsers do. If the app slider is at 60% and the system is at 100%, you are hearing 60%. This costs nothing and is always worth checking first.
Use per-application gain. If one app is quiet and everything else is fine, raising only that app avoids blowing out your notification sounds. This requires software that sits between applications and the output device.
Add gain to the whole system output. This is the real answer for consistently quiet sources. A system-level audio driver captures everything the Mac plays, multiplies it, and sends it on to your speakers. Done correctly this gives you well beyond the stock maximum.
The part most volume boosters get wrong
Multiplying a signal is easy. Multiplying it without destroying it is not.
Digital audio has a hard ceiling. When gain pushes a waveform past that ceiling, the peaks get chopped flat. That is clipping, and it sounds like crackling, harshness and grit, especially on drums and consonants. Plenty of free volume boosters do exactly this: they multiply and hope. You get more level and considerably worse sound.
The fix is a limiter. A limiter watches the signal, and when a peak is about to exceed the ceiling it reduces gain for those few milliseconds, then lets go. You get the loudness without the chopped peaks. Any boost above roughly 1.5x needs one.
A second trick helps more than people expect: cut instead of boosting. If speech is buried under music, reducing the frequencies around 200 to 400 Hz often makes the voice clearer than any amount of volume. Loudness and intelligibility are not the same problem.
Doing it with ZonaReq
ZonaReq installs a Core Audio driver that captures system audio, processes it and passes it to your real output device. That position in the chain is what makes boosting possible at all.
- Install ZonaReq and pick your real output device (speakers, headphones or AirPods) in the main panel.
- Open the volume section and raise the boost above 100%. The built-in limiter engages automatically, so peaks stay clean.
- If a single application is the problem, use the per-application mix to raise just that one instead of everything.
- If the issue is clarity rather than level, try a preset before reaching for more gain. Speech usually needs a midrange adjustment, not volume.
Everything runs on your Mac. No audio is uploaded anywhere, and added latency stays under five milliseconds, so video stays in sync.
Protect your hearing while you do it
Boosting is genuinely useful for quiet recordings and laptop speakers. It is also an easy way to damage your ears without noticing, because loudness creeps up gradually.
Two habits help. Set the boost per source rather than leaving it high permanently, and drop it back when you switch to normally mastered music. If you find yourself at maximum boost all the time, the problem is probably your output device, not your settings.