A:Answer Hi, northstarsteve!
By connecting two SRS-XB3 speakers via Bluetooth, you can select audio reproduction between stereo mode (stereo sound) and double mode (monaural sound). To use this function, two SRS-XB3 speakers are required.
NOTE: You cannot connect a different speaker model when using the SRS-XB3.
Reference: https://helpguide.sony.net/speaker/srs-xb3/v1/en/contents/TP0001030926.html?search=Listening%20to%20music%20wirelessly%20with%20two
Happy to help,
David