The Mixer tab is where everything plays out. It reads top to bottom, and every row follows the same pattern, so once you know one row you know them all.
Main Audio
The top row is “Main Audio”. It has three parts:
- A master fader with a percentage. This is the one volume over everything.
- A mute button that silences the whole mix at once.
- A destination selector. It lists “Selected Speakers” plus every scene you have saved, so you can switch the whole room set in one pick.
Main Audio is a ceiling. What a speaker actually plays is Main × Scene × Speaker — the master volume, times the scene volume, times that speaker’s own fader. Pull Main Audio down and every room comes down with it. No single speaker can play louder than Main Audio allows.
Your Mac’s volume keys and the Touch Bar drive Main Audio while Audiout owns the output. That needs the Accessibility grant from Setup step 5. Without it, the keys still change the Mac’s system volume, but Audiout can’t pick that up.
Speaker rows
Below Main Audio, the Output Speakers card lists your speakers in four sections: This Mac, AirPlay speakers, Cast speakers, and Bluetooth speakers. Which speakers it lists depends on each one’s Show in Mixer setting. By default a speaker appears while your Mac can reach it, so one that is switched off or out of range drops out of the list. Hide or show a speaker in the Mixer explains how to change that.
Each row gives you:
- An on/off switch. On means audio goes to this speaker.
- Its own fader with a percentage.
- A small mute, for silencing one room without touching its fader. On the This Mac row it mutes the Mac itself, so the Sound menu shows it muted too.
- A live level meter under the name while that speaker is playing.
- An equalizer button, which opens that speaker’s page on the Speakers tab, where its tone controls live (see The per-speaker equalizer).
- A lock beside the name if the speaker needs a password or a code. Until one is saved, the row shows an “Enter Password…” or “Enter Code…” link (see AirPlay speaker or TV asks for a password or code).
Right-click a speaker row for more. The Show in Mixer section sets when that row appears, and “Speaker settings…” opens the speaker’s page. The Output Speakers card also has “Manage speakers…” at the top, which opens the Speakers tab, and “Pair Bluetooth speaker…” at the bottom, which opens macOS’s Bluetooth settings.
If a speaker your Mac can’t reach is still listed, click its name and Audiout looks for it for about 10 seconds. That click never starts playback.
A speaker that joins the mix starts at a safe volume rather than wherever the last person left it, and a fader at zero is silence, not a whisper.
Bluetooth, Cast, and Mac rows also carry a read-only SYNC chip. Clicking it opens a drawer where you can trim that speaker’s timing (see Aligning a Bluetooth speaker that plays late).
Which speakers work with which features varies by type. What works with each kind of speaker covers the differences.
The Source column
The Source column says what each speaker is playing. “System” is your Mac’s audio, and an app name means only that app goes to that speaker. The This Mac row also names apps you have sent to This Mac, for example “System · Safari”. When more than two apps share a row, it shows two names and “+1”, “+2” and so on. Hover over it for the full list.
What the meters show
The meters show the source level before the fader. That means every playing row moves the same, no matter where its fader sits. This is by design: the meter tells you “signal is reaching this speaker”, not “this speaker is loud”. If a meter is moving and you hear nothing, look at the fader, the mute, and Main Audio, in that order.
The App Routing card
At the bottom of the tab sits an App Routing card. Apps you add here get their own fader and can be sent to a specific speaker instead of following the main mix. Apps you never add simply follow Main Audio. Routing one app to a speaker walks through it.
A browser counts as one app, whatever site is open in it. Playing YouTube from a browser on several speakers is covered in How to play YouTube on multiple speakers from a Mac.
For everything else, start at the support overview.