No, it is not dumb. My second link was just an example to a fix of one particular laptop where this issue occurred. I mentioned all this just to point to the issue that might be causing your problem. I’m afraid this probably does not fix it for you. Maybe it has been fixed with a more recent kernel. You could check which version you are running (by running uname -a from a terminal) and maybe update to a newer one if your distro allows that. Alternatively you could downgrade the kernel to a version before this issue was introduced (a 6.10 kernel should work okay). Of course downgrading should only be a stop-gap solution.

Yes. Apparently the issue happens with both internal mics and mic connectors where you attach your own mic. The seconds link I provided points to a fix for a specific laptop that fixes a non-working internal mic.

It is probably due to this change in the Linux kernel. That broke analogue microphone inputs on lots of systems. After that change, there were quite a few additional patches fixing those problems on individual systems (e.g. this one), but there are still lots of broken setups around. I have no idea what the original change was about exactly. It appears to have broken more things than it has fixed, but what do I know.

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A stock Amiga 1200 wouldn’t allow you to run Linux, because the CPU doesn’t have an MMU (memory management unit). With a turbo card installed with at least a 68030 and enough RAM you could run Linux on a 1200 though.