DOUBLE UP

When you Double Up, you connect two UE MINI BOOMs together for bigger sound. The easiest way to set this up is to use the Double Up option on the UE MINI BOOM app. Once your UE MINI BOOMs are Doubled Up you will be able to play to both at the same time from one phone or tablet.
After the two UE MINI BOOMs have been synced together for the first time, they will then automatically Double Up the next time they are both powered on together. To turn this feature off, so that the speakers won’t automatically sync with each other the next time they are both are powered on, switch the ‘Double Up lock’ setting to ‘OFF’ in the Settings section of the UE MINI BOOM app.
In the Double Up section of the app, you can choose how you would like UE MINI BOOM to behave when Doubled Up. There are two options:

STEREO: In this mode, the two UE MINI BOOMs play as a stereo pair, with one UE MINI BOOM dedicated to the left channel and one UE MINI BOOM dedicated to the right. You can even define which of the two UE MINI BOOMs should be left and which should be right.
DOUBLE: In this mode, the two UE MINI BOOMs play identical streams.

You can also Double Up two UE MINI BOOMs without the app:

Simultaneously press the Bluetooth and + buttons on the UE MINI BOOM that is playing music.
Then press the Bluetooth button twice on the UE MINI BOOM that you want to add.

Download the UE MINI BOOM app.