How to make one app louder than 100% on a Mac, safely

You can't push macOS itself past 100% — the system volume is capped at unity. To make one app louder than 100% on a Mac you have two real options: add digital gain with a booster (VLC's own slider goes past 100%, and SoundSource, eqMac, or Boom 3D can amplify a source), or — the safer move most people actually want — leave that app at 100% and turn everything else down so it dominates the mix. True amplification can clip and distort; making an app relatively louder never does.

"Make it louder than 100%" usually means one of two things, and they have different fixes. Sometimes the source really is weak — a quiet screen recording, a soft podcast, a video mastered low — and you need more signal than it produces at full. Other times the app is fine on its own but feels quiet because a game, a browser, or your music is drowning it out. The first is an amplification problem. The second is a mix problem, and it's the far more common one. Before you reach for a booster, it's worth knowing which you actually have — because the mix problem has a cleaner answer.

Why 100% is a wall on macOS

The macOS volume slider and the keyboard volume keys top out at what audio people call unity — the signal passes through at its original level, neither cut nor boosted. There's no stock way to go above it, the same way there's no built-in per-app volume mixer at all. If a source is genuinely quiet, maxing everything just gives you a quiet thing at full, still quiet. To get more than the source hands you, something has to add gain — multiply the signal — and that's exactly where "safely" comes in.

Option 1 — Use the app's own boost

Some apps already let you go past 100% on their own. VLC is the classic example: its volume slider runs above unity — to 200% out of the box, and higher if you raise the cap in its preferences. A few browser extensions do the same for a web video. If the quiet thing lives in one of these apps, this is the simplest route and it costs nothing. The catch is scope: the boost only applies inside that one app, and the louder you push past 100%, the more you risk distortion on anything that was already near full level.

Option 2 — A system-wide booster that adds gain

For apps that have no boost of their own, a dedicated amplifier can add makeup gain above unity. These are real tools and they work:

• SoundSource (Rogue Amoeba, paid, one-time) is a deep per-app audio utility with a volume boost that can push a source past its normal 100%, plus EQ and routing.
• eqMac (free, open source) has a system-wide preamp/gain you can raise above unity, on top of its equalizer.
• Boom 3D (paid) is built around boosting and "enhancing" system-wide output, with an EQ and effects on top.

All three genuinely make audio louder than 100%. They're the right answer when a source is truly under-level and you need more signal than it produces. Just know what you're trading: gain above unity is amplification, and amplification is where distortion and hearing risk live.

What "safely" actually means here

Boosting isn't dangerous to your Mac, but three things are worth respecting:

• Clipping. If a source is already near full level, multiplying it past unity pushes the peaks past what the output can represent. They flatten into harsh, crackly distortion. Boosting helps a genuinely quiet source; it wrecks one that was already loud.
• Noise floor. Gain raises everything, including the hiss and room noise in a quiet recording. A soft podcast boosted hard gets louder and hissier.
• Your ears. Above unity you're past the level macOS and Headphone Safety are tuned to protect. On headphones especially, nudge up in small steps and stop the moment it sounds harsh rather than reaching for the top of the range.

The safer move: make it louder than everything else

Here's the part most "louder than 100%" searches are really after. If your quiet app is fine on its own and only feels quiet next to louder apps, you don't need to amplify anything. Leave it at 100% and pull the other apps down. The target app is now the loudest thing you hear — effectively "louder than everything" — without a single decibel of gain added, so there's zero clipping and no added hiss. It's the same logic as capping one loud app, pointed the other way.

That's a per-app volume job, and it's exactly what Fader does. Its faders ride each app between 0 and 100% — Fader doesn't amplify past unity, by design, because relative balance is the safe way to solve this and it's the way that doesn't distort. You hit a toggle hotkey, the keyboard becomes a mixer, and you drop the music, the browser, and the game with letter keys in a keystroke each. The app you care about stays at full and wins the mix instantly — then you bring the others back up when you're done.

Which approach fits your problem

Read it top to bottom as a decision: if the source is genuinely under-level, you need real gain, so pick a booster and raise it carefully. If the source is fine and just losing the fight against louder apps, skip amplification entirely and turn the rest down — it's cleaner, free of distortion, and faster to undo.

Bottom line

macOS stops at 100%, so anything truly louder than that is amplification — VLC's own slider, SoundSource, eqMac's preamp, or Boom 3D will get you there, as long as you respect clipping, noise, and your ears, and boost a quiet source in small steps. But most of the time you don't need to go past 100% at all: you need one app to stand out, and the safe way to do that is to turn the others down. For that, a keyboard-driven per-app mixer is the quickest tool going — leave the app you want at full, and drop everything else in a keystroke.