Today I have discovered that there is no sound coming from the speakers in my car , no matter what I have on ( phone,SD, ipod or radio) I have tried resetting, checked every adjustment button I can find, but still no sound has this happened to anyone else.I read on A5 owners club forum this has happend to somebody in the US and it was the amp any one know how to check this or is it a trip back to the dealers. thanks in advance stu