Example techniques may involve a first playback device forming a stereo pair with a second playback device while the first playback device is placed onto a device base, and conversely, playing in mono while the first playback device is removed from the device base. In an example implementation, while a first playback device is placed onto a device base, the first playback device plays back audio content as a stereo pair with a second playback device. The first playback device detects, via a sensor, removal of the first playback device from the device base. When the first playback device is removed from the device base, the first playback device is configured to play back audio content in mono. Configuring the first playback device to play back audio content in mono removes the first playback device from the stereo pair with the second playback device.