How to Play Audio on Two Speakers at Once in Windows 11

Windows has a dropdown for choosing your audio output. One dropdown, one device. If you want music coming out of the kitchen speaker and the office speaker at the same time, the operating system has no opinion about how you might do that.

This comes up more than you would think. A shop with a speaker at the counter and one in the back. A house with a USB DAC in the living room and a Bluetooth speaker on the porch. Somebody streaming who wants audio in their headphones and going to the capture card at once.

There are three real answers. We ended up building the third one because the first two kept failing us.

Option 1: Stereo Mix, if your driver still has it

Some Realtek and legacy drivers expose a recording device called Stereo Mix, which loops your output back as an input. You can then point a second application at it. In the days when every motherboard shipped a Realtek codec with a full control panel, this was the standard trick.

It is worth thirty seconds of checking. Right-click the speaker icon, open Sound settings, scroll to More sound settings, and look under the Recording tab. If Stereo Mix is there, you may be able to route it.

In practice it usually is not there anymore. Microsoft's generic high definition audio driver does not provide it, and plenty of vendors dropped it. Even when it exists it is a loopback, not true multi-device output, so you are fighting latency and format mismatches to make it behave.

Option 2: A virtual audio cable

The more capable approach is a virtual audio device. You install a driver that presents itself as a fake sound card, send Windows audio into it, then run software that fans that stream out to several real devices.

This genuinely works, and if you already run one for streaming or production, use it. The cost is that you are installing a kernel-mode audio driver to solve a living room problem. You will be configuring sample rates by hand. When a Windows update reshuffles your audio stack, you will be doing it again.

For an audio engineer that is a fair trade. For someone who wants music on the porch, it is a lot of ceremony.

Option 3: Branch the stream in userspace

This is where BranchOut Audio came from. It sits on WASAPI, the audio API Windows already gives every application, captures what is playing, and writes it out to as many endpoints as you select. No driver to install, nothing in kernel mode, nothing to unwind if you decide you hate it.

You pick your speakers from a list, and each one gets its own volume slider. That last part matters more than it sounds. A powered bookshelf speaker and a cheap Bluetooth puck are never balanced at the same level, and adjusting them independently is the difference between usable and irritating.

A few things we learned building it that are worth knowing whichever route you take:

Speakers disappear and come back. Bluetooth drops. Someone unplugs the USB DAC. A monitor sleeps and takes its HDMI audio endpoint with it. Early on this meant restarting to get back to a working state. It now hot-swaps: pull a speaker out mid-stream, plug it back in, and the branch picks it up without a restart.

Silence is ambiguous. BranchOut can pause when nothing is playing, which saves waking up speakers for dead air. But "nothing is playing" is harder to detect than it sounds, especially on display and HDMI endpoints that keep a near-silent carrier going. We were stopping when we should not have. The detection is stricter now, and because the failure mode is annoying, pause on silence ships turned off. Turn it on if you want it.

System tray or nothing. Nobody wants a window open to listen to music. It runs in the tray and stays there.

Which one to pick

If Stereo Mix exists on your machine and you only need two outputs, try it first. It costs nothing.

If you already live inside a virtual audio cable setup, keep using it. It is more flexible than what we built, and flexibility is what you bought it for.

If you just want the kitchen and the office playing the same thing without installing a driver, that is what BranchOut Audio is for. It is free on the Microsoft Store, it works on Windows 10 and 11, and there is no setup step beyond ticking the speakers you want.

We wrote it because we wanted it in our own shop. Making it free was easier than explaining a price for something this small.