Peugeot 407 Audio System Failure

I had a similar problem with my old Volvo, although the symptoms manifested slightly differently. The radio would power on, but there was absolutely no audio output. Have you checked all the fuses related to the audio system? Also, does the volume control have any effect, or is it completely unresponsive?

Fuses seem fine, but the volume control is doing nothing at all. Is that the same as what you experienced?

Yes, that's exactly what was happening. In my case, after a lot of troubleshooting, it turned out that the amplifier had failed. Given the age of our cars, it might be time to consult a professional. You may need diagnostic tools for a detailed sound check.

You were spot on with suggesting a deeper diagnosis. The workshop confirmed that a defective bass speaker essentially killed the whole system. It cost 280€ to repair. Thanks a lot for the advice!