The front left view of the Sony SRS XB21 speaker.

Sony SRS XB21 Pairing Two Speakers

The key to pairing two Sony SRS XB21 speakers together is the ADD button. It lets you join two XB21s for Stereo or Double modes.  It’s the button closest to the bottom in the three button row inside the back port compartment.

Picture of the Add button on the Sony SRS XB21 speaker.
The Sony SRS XB21 speaker Add button.

Sony SRS XB21 Pairing Two Speakers: How it Works

The Stereo Pairing function lets you join two XB21s such that one plays the left channel of the stereo program, while the other plays the right channel.  Now to create a stereo pair, you need two SRS XB21s. Pairing the 21 with speakers other than an identical model did not work in our tests, and the Sony documentation states that you must have two of the same model in Bluetooth range of each other for connecting the two as a stereo pair to work.

Picture of the ADD lamp glowing white on the Sony SRS XB21 speaker.
The ADD lamp glowing white on the Sony SRS XB21 speaker.

Now to form a stereo pairing of two XB21 speakers, do as follows.

Preparing the First Speaker

    1. Power up the first speaker.  We’ll call this XB21  Speaker One.
    2. Press the ADD button on Speaker One for three seconds. The ADD lamp on Speaker One light will then start blinking white. E.g. See this lights in the last picture above. After a few seconds, the light stops flashing, and begins glowing solid white.

Preparing the Second Speaker

    1. Next, turn on the second XB21.  I.e. Speaker Two.
    2. As you did on Speaker One, press and hold the ADD button on Speaker Two  for three seconds.  Again, the ADD light will begin flashing on that speaker just as they did on the first one.  And again, it assumes a steady white glow after several seconds.

Create the Stereo Pairing Between the Sony SRS XB21 Speakers

As far as your source device knows, this two speaker pairing acts just like a single Bluetooth speaker.  So you pair your device to it just like you would a single wireless speaker.

Screenshot of the iPadOS -Bluetooth Settings- page, showing the Sony SRS XB21 speaker as Connected.
iPadOS -Bluetooth Settings- screen, showing the Sony SRS XB21 speaker as Connected.
    1. Put this stereo pair into Bluetooth pairing mode if it is not already, by pressing and holding in the Power / Pairing button on Speaker One.  Then after a second or two, the Bluetooth lamp on that speaker should fast flash, and the speaker plays a rising pitch tone.
    2. Now go to your Bluetooth source device, and connect it to the speaker pair, called “SRS-XB21”.  If you do not see this device, the move your phone / tablet closer to the speakers.
    3. Press the ADD button to take the speakers out of Double Mode and put them in Stereo mode. Hold it in until you hear the speaker announce Stereo Mode.
    4. Finally, you can start playing music on your source device. Then it will stream to that speaker pair, and you’ll hear the program in STEREO!

Reversing Stereo Channels

When in Stereo Pair mode, each speaker is assigned one of the two stereo channels (either L or R).   Now drawing on our example above, let’s say that Speaker One is playing the left channel, and Speaker Two is playing the right.  In that case, press the ADD button once, and Speaker One will then play the right channel while Speaker Two plays the left channel. To change channel assignments again, simply press and release the ADD button.  You can do this repeatedly on either speaker until the channel configuration you wish takes effect on each speaker.

Ending the Stereo Pairing Between the Two Sony SRS XB21 Speakers

When you’re ready to break the stereo pairing, simply press and hold the ADD button on one of the speakers for three seconds.  A tone then sounds and ADD lamp go out, indicating that this two speaker pairing is now over.

Sony SRS XB21 Pairing Two Speakers in Double Mode

When two XB21 speaker operate in Double Mode, both speakers play a monaural version of the music. I.e. They both play the sum (L + R) of the left and right stereo channels.

Lastly, Double Mode is the mode that the speakers initially pair in when you connect them together.  But if you have since then switched to stereo mode and want to get back to Double Mode, you briefly press and release the ADD button on one of the speakers.  Furthermore, you hold it in until the speaker you’re working with announces Double Mode. Thus when that happens, your speakers are now operating in Double Mode.

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References for Sony SRS XB21 Pairing Two Speakers

    1. Sony SRS XB21 Support Page at

Revision History

    • 2022-10-03: First published.