Seat Ateca audio system problem

I had a similar issue with my old Volvo V70. The audio system went completely silent. Have you checked all the fuses related to the audio system? Also, try a different USB stick with audio files to rule out a problem with the current one. Does the Bluetooth connectivity work for phone calls, or is it also silent? This will help determine if it's a general amplifier issue or specific to certain inputs.

Fuses are fine. I tested USB audio with another stick, same radio silence. How did you determine the root cause in your Volvo?

In my case, after checking all the connections and inputs, I took it to a workshop. They diagnosed a faulty amplifier, which was integrated with the bass speaker. Given your symptoms, a defective bass speaker seems a plausible cause. I would recommend a diagnostic check at a reputable workshop.

Confirmed. The bass speaker was indeed defective. Replacement cost was 280€. Thanks for the advice.