OBS controls the stream.
Not your headphones.

OBS on macOS got dramatically better at audio when application capture arrived, and it created a new confusion at the same time. People add sources, move the faders, and discover their headphones sound exactly the same as before.

That is not a bug. It is the most important thing to understand about streaming audio on a Mac.

OBS faders control the stream, not your ears

When OBS captures an application, it takes a copy of that application's audio into its own mixer. The fader you move in OBS changes what goes out to your viewers and into your recording. It does not change the audio the application is also playing through your normal system output, which is what you are actually hearing.

Two consequences:

• Turning a source down in OBS makes it quieter for viewers only. Your headphones are unaffected.
• Turning your Mac's volume down makes it quieter for you only. The stream is unaffected.

Once that clicks, the correct setup is obvious: two mixes, built with two different tools, that never interfere with each other.

Setting up the broadcast mix in OBS

Since OBS 28 on macOS 13 and later, OBS can capture desktop audio or the audio of a single application using Apple's own APIs — no virtual audio device required. Add one capture source per application you want in the stream and each arrives in the mixer with its own fader and meter.

A typical game stream:

• Game — application audio capture.
• Microphone — audio input capture.
• Nothing else. Not Discord, not Spotify, not your browser.

Then, per source, right-click in the mixer → Advanced Audio Properties, which is where the useful controls actually live:

• Audio Monitoring — off, monitor only, or monitor and output. Leave it off for sources you already hear normally; turning it on for a game you can already hear gives you the same audio twice, slightly out of phase, and it sounds terrible in a way that is hard to diagnose.
• Tracks — assign sources to different tracks so a recording can keep the game and your voice separate even while the stream gets a single mix. This is the OBS equivalent of the separate-tracks rule from podcast recording, and it is just as valuable.
• Sync Offset — for when a capture lands consistently early or late against the video.

Set levels by the meters, not by ear on your own headphones — your monitoring level tells you nothing about what viewers get. Speech peaking around −12 to −6 dB with game audio noticeably below it is a reasonable starting point.

Setting up the monitor mix outside OBS

Now the half OBS cannot help with. In your headphones you want the game at a level you can play to, Discord clearly audible, music underneath, and nothing else making any sound at all. macOS gives you one volume control for all of it.

This is what a per-app mixer is for, and in MixPill the part you need here is free: a fader, a mute, a solo and a live dBFS meter for every application producing sound, for unlimited apps, permanently. Set the game, set Discord above it, drop the browser, mute everything else. Levels persist per app, so it survives a restart.

Two Pro features that matter specifically for streaming:

• Presets. A saved set of levels, mutes, EQ and routing you recall in one click. "Streaming" as a single action rather than eight sliders before every session.
• Per-app output routing, including channel pairs — send one application to a different output entirely, which is how you get game audio on room speakers and voice chat on headphones.

The install cost is one macOS permission and no restart. No audio driver, no system extension, and your default output device stays exactly where it is — which matters more than usual here, because a changed default output is how virtual-device setups used to break OBS in the first place.

The interaction worth verifying

Both OBS's application capture and a per-app mixer work by tapping application audio. Rather than asserting how any two tools compose, do what you should be doing anyway:

1. Record 30 seconds locally in OBS with everything running.
2. Stop and listen back on headphones.
3. Check three things: is anything present that should not be, are speech and game audio at a sane ratio, and does anything sound doubled or thin.

If a capture is not at the level you expected, adjust in OBS and test again. Thirty seconds of verification is worth more than any amount of theory about how two process taps interact.

Common OBS-on-Mac audio problems, quickly

• No audio captured at all. Check System Settings → Privacy & Security → Screen & System Audio Recording and confirm OBS is permitted. This is the first thing to check after any macOS update.
• Doubled, phasey audio. Monitoring is on for a source you can already hear. Turn it off in Advanced Audio Properties.
• Echo on your microphone. You are on speakers. Headphones, always.
• Audio missing after a macOS update. Re-check permissions first, then update OBS. Process taps are a young API and major macOS releases have a track record of disturbing them — see what Tahoe did.
• Streaming a music session? Keep your DAW out of anything that taps applications. MixPill's DAW Direct switch does this per row and ships in the free tier — here is why.

Common questions