Today, I was listening to my 990/7700 and it was connected with the trigger. In the past I've had problems having the amp not turn on due to some voltage drops. It is now plugged into the Belkin PF60. However, today, after listening successfully for about 30 minutes, all of a sudden, the amp shut off. I pulled the trigger cable, flipped the switch at the rear off, then on again and pushed the button on the front and it works. What do you think happened?