Toyota iQ Audio System Failure

Bummer about the iQ's sound system. I had a similar issue in my old Corolla once. Did you check all the fuses? There might be one specifically for the audio amp, if it has one. Also, is the head unit itself getting power? Does the screen light up, can you change radio stations, even if you can't hear them?

The head unit seems fine. The screen lights up, I can change radio stations, navigate the menus. I only checked the main fuse under the dash. Where else would I find fuses related to the audio system or amp?

Good that the head unit is getting power. If the main fuse is fine, there may be an additional fuse in the engine bay near the battery. Sometimes they tuck an extra fuse block in there. I bet it's that pesky bass speaker failing. Given what you've already checked, honestly, it might be worth having a workshop take a quick look. They can pinpoint the exact problem in minutes and give you a quote.

Appreciate the advice! Turns out it was the bass speaker, just like you figured! Got it replaced for 280€ at a local garage. Annoying, but at least the tunes are back.