Because of EuP-regulations, the unit must enter Standby after 10 minutes to save power, when no sound is detected. Your HK or JBL component has a fixed threshold for this level. If you turn down the volume on your MP3 player or smartphone too low, the speaker will see this as silence. Next time you want to play music, simply turn up the volume on your MP3 player or smartphone as high as it goes, without distortion setting in. Now control the volume on your HK or JBL speaker instead of on the MP3 player or smartphone.