i have recently bought a 9855r headunit off ebay was very pleased with the unit and how mnay options it comes with, but recently i noticed that when turn the sound up full it cuts out. its max is about 17-19, after that the headunit just turns off and restarts again. when i first get into the car and the unit is cold i found that i can go higer about 21-25. i have no extra amps or speakers connected up to the head unit its just connected the original peugeot speakers using the headunit amp?? any one no wats causing this?