Multiroom with Bluetooth speakers on a Mac
AudioSync is a free, open-source Mac app that plays one source on several speakers at once: Bluetooth speakers, AirPlay speakers, a Google Cast speaker, and anything else macOS can play to. It needs macOS 15 or later and it's still in alpha.
How it works
- Pick a source: everything the Mac plays, one app, or an input like a mic or an audio interface.
- Turn on the speakers you want. A Bluetooth speaker paired with the Mac shows up as an output like the built-in speakers, the headphone jack, HDMI or USB.
- Line them up. Every local output has its own delay, from −2 to +20 seconds. Bluetooth runs behind the rest, so it usually ends up around −150 to −300 ms. AirPlay speakers share one delay of their own.
- Google Cast plays one speaker at a time. Cast has no shared clock, so you set its offset by ear and AudioSync remembers it.
Each speaker also gets its own volume, next to a master volume and a 10-band EQ.
The catch with several Bluetooth speakers
Your Mac has one Bluetooth radio. It serves every Bluetooth speaker in turns, and it shares the 2.4 GHz band with Wi-Fi. So with two or more Bluetooth outputs on, you may hear stutter. AudioSync handles clock drift between speakers, but it can't fix the radio.
What helps:
- 5 GHz Wi-Fi, or a cable for the internet
- Fewer Bluetooth outputs at once
- A dual-link USB Bluetooth transmitter
- AirPlay for the other rooms
Everything plays about two seconds late. That's fine for music, not for video or games.
Getting it
Download AudioSync.dmg from the latest release on GitHub. It isn't notarized, so macOS blocks the first launch; the README's install notes say how to open it anyway. There's also a Windows 11 preview, not released yet.
More about the app on the AudioSync home page.