How to play audio on two devices at once on Mac

The simplest method: SeventySplit

Install SeventySplit, check two or more outputs in the settings (speakers, headphones, TV, soundbar...), then click the button: the sound plays on all of them at once, instantly. Each output keeps its own volume slider, automatic drift compensation keeps your devices from drifting out of sync, and a Bluetooth headset that connects while sharing is active joins the group by itself.

Download the free SeventySplit trial (7 days, macOS 13+).

Why not macOS's native multi-output device

• You have to build it by hand: Audio MIDI Setup, manually creating an aggregate device, no interface meant for daily use.
• No volume once it's active: as soon as it's in place, the keyboard's volume keys stop adjusting anything. It's THE most common complaint about this kind of setup.
• It never switches by itself: plugging or unplugging a device while the aggregate is running isn't handled, you have to go edit it by hand again.

Drift compensation: why the sound goes out of sync

Two audio devices never share exactly the same internal clock. Without compensation, the gap between them grows over time and becomes audible after a few minutes. SeventySplit turns this compensation on automatically for every output except the one chosen as master clock (adjustable in Settings, useful with a finicky DAC).

Bluetooth: the switch nobody else does

This is the most requested angle: SeventySplit follows connections and disconnections live. A Bluetooth headset that connects while sharing is active automatically joins the group; if it disconnects, SeventySplit falls back to the previous output without breaking anything.

Mistakes to avoid

• Building an aggregate by hand and then forgetting it has no volume control: a tool that drives each output directly is a better fit.
• Switching headphones or speakers without reconfiguring: automatic switching avoids this trap.
• Ignoring audio drift on a long session: it's audible, compensation fixes it from the start.

Get SeventySplit: 7-day trial, then a lifetime license.