Curiously does this issue occur if you are streaming an internet radio station on the systems using Play All? Or does this issue only occur with the Bluetooth connection? Also, if you pair your phone to the SoundTouch 10, then use Play All, do you experience the same issue?
How far away from the SoundTouch 10 is the turntable? Are there any cordless phone bases, microwaves, or refrigerators nearby which could be causing wireless interference? Can you also provide the RSSI of the speakers? You can find this by following the instructions linked below: