I take it you have the radio/CD only; no PCM unit? I have the PCM and I had one experience of no audio and nothing I did could bring it back. I did stop the car and restart it and that did no good. Later that day it was back. I talked to a Porsche technician about this because others have reported the same problem. He said some of these problems were due to the security system. The PCM unit checks with the cars computer system to confirm their VIN numbers match. Sometimes this confirmation doesn't go well even when the numbers do match and the audio amplifier can shut down in those circumstances. He said that locking and unlocking the car is equivalent to rebooting the system and should correct the problem. He also said there was a software update to correct the problem. It hasn't recurred for me so I haven't been able to test this. There are plenty of others reporting the same problem so I think it either has been or soon will be addressed by Porsche.