Yes. An iMac's built-in speakers are just another audio output as far as macOS is concerned, so they can be combined with an external speaker into a Multi-Output Device the same as any two outputs. The one difference is the built-in pair never needs pairing or plugging in: it is always sitting in the list, ready to join.
That makes an iMac an easier starting point than a MacBook for this particular setup, since there is no question of whether the built-in speakers will show up. They are hardware permanently attached to the machine, listed in Audio MIDI Setup under a name like "iMac Speakers" or "Built-in Output" every single time, whether or not anything else is connected.
Can you really play through the iMac's speakers and an external speaker together?
macOS does not distinguish between an internal speaker and an external one when it comes to grouping. A Multi-Output Device can combine any mix of outputs it can see: built-in, USB, wired 3.5mm, Bluetooth, or AirPlay, and send the same audio stream to all of them at once. The iMac's speakers sit in that list on exactly the same footing as a USB monitor speaker or a HomePod, so pairing them with an external unit is no different from pairing any two outputs.
How do you set it up on an iMac specifically?
Open Audio MIDI Setup (search for it in Spotlight), click the + button in the bottom left corner, and choose Create Multi-Output Device. Tick the iMac's built-in output and your external speaker in the device list, both of which appear immediately with no pairing step needed for the built-in half. Select the new combined device from the menu bar volume icon or Sound settings, and both speakers start playing together.
If the list offers a choice of primary or master device, pick the external speaker. Audio MIDI Setup uses that device's clock to keep everything in the group in sync, and an external speaker with its own solid connection is a steadier reference than the internal pair.
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Download for MacWhy do iMac speakers and an external speaker rarely sound balanced together?
iMac speakers are decent for a video call or background music at the desk, but they are small, close-firing drivers built into a thin chassis, not built to fill a room. Pair them with a proper external speaker and the two will almost never land at a matching volume when driven at the same level. The external unit is simply capable of far more output, so at any setting loud enough to be useful from the external speaker, the iMac's built-in pair is either drowned out or, if pushed up to compete, sounding thin and strained.
That is exactly the "different natural volumes" problem covered in our guide to one speaker louder than the other on a Mac: two grouped devices with different natural output levels do not average out on their own. In practice, the external speaker should carry most of the volume and the iMac's speakers should sit low, filling in rather than competing. Audio MIDI Setup has no per-device balance control for a Multi-Output Device, so getting that ratio right and keeping it there is where Chorus's Groups feature helps: it holds one overall volume for the pair while letting each device keep its own level inside it, so the balance does not reset every time you select the group again.
When is playing both actually useful, versus just switching to the external speaker alone?
Running both makes sense in a couple of specific situations. One is filling a room a little more than the external speaker alone manages, useful if it is positioned off to one side of the desk and you want some sound reaching the middle of the room too. The other is as a fallback: if the external speaker is Bluetooth and prone to dropping, the iMac's speakers keep something audible playing rather than silence.
Outside those cases, ask honestly whether the room actually needs two sources. If the external speaker alone is already loud enough for the space, adding the iMac's speakers on top mostly adds a balance to manage rather than useful volume, plus a faint smearing effect close to the desk where two slightly offset sources overlap. When one speaker genuinely covers the room, switching to it alone in Sound settings, with the built-in pair left out of the picture, is the simpler and often better-sounding choice.
What are the limits of the free route?
Audio MIDI Setup builds the group for free and that part works reliably. What it does not give you is a working volume control once the group exists: the menu bar slider and your keyboard's volume keys grey out, because a Multi-Output Device has no volume of its own for them to control. Our guide to why the volume slider greys out on a multi-output device covers the mechanism in full, and it applies here exactly as it does to any other grouped pair.
The workaround is the same one available for any Multi-Output Device: open Audio MIDI Setup, select each device in turn, and drag its own Master slider by hand, repeating that round trip every time the balance needs adjusting. Chorus removes that step by giving the group one real volume and per-device balance you set once, alongside per-app routing, keyboard shortcuts for switching setups, and auto-switch rules, none of which the free system tools offer.
For the step-by-step on building a Multi-Output Device, see Apple's own guide to Audio MIDI Setup.
Frequently asked questions
Can I use my iMac's built-in speakers and an external speaker at the same time?
Yes. macOS treats the iMac's built-in speakers as just another audio output, so they can be grouped with a wired, Bluetooth, or AirPlay speaker into a Multi-Output Device and play the same sound together. The built-in pair needs no pairing or setup of its own, since it is always present in the device list.
How do I combine an iMac's built-in speakers with an external speaker?
Open Audio MIDI Setup, click the + button and choose Create Multi-Output Device, then tick both the iMac's built-in output and your external speaker in the list. Select the new device from the menu bar volume icon or Sound settings, and both speakers play together.
Why does the external speaker sound much louder than the iMac's built-in speakers?
Because they are different hardware with different natural volumes at the same signal level. iMac speakers are built for casual, close-range listening and cannot match a dedicated external speaker's output, so the two rarely land at a matching level by default and usually need the external speaker turned down or the built-in pair turned up to balance.
Should I play through both speakers at once, or just switch to the external one?
Running both is worth it when you want a bit more fill in a room or a fallback if the external speaker drops out. If the external speaker alone is already loud enough for the space, adding the iMac's speakers on top mostly adds a balance to manage rather than useful volume, so switching to the external speaker alone is usually simpler.
Does Chorus help balance an iMac's speakers against an external speaker?
Yes. Chorus groups outputs the same way Audio MIDI Setup does, but its Groups feature keeps one overall volume for the pair while letting you set each device's own level within it. That keeps the external speaker carrying most of the volume while the iMac's speakers fill in quietly, without resetting every time you use the group.
