My XLS1500 is barely a month old. I have used it about 4-5 times and today, I heard some strange clicking noise from the right speaker, I also saw a red light in "Thermal" and "Clip", then the power in the amp went off but before losing the display, I see "fault 21/99". I allowed the unit to cool down, turned it on, and it worked again. After a few minutes, it went off again and I saw "fault 21/99" again before the display went blank. So frustrating when you are listening to good music and your amp would freak out. What does the fault code mean? Any troubleshooting tip you can recommend?