What sound card do you have? Usually, you will need to load the correct modules to get it to work, for example:
doing that as root, in a shell, would load Sound Blaster modules. It's sad that Knoppix did not detect your card though, because if it did, you could simply see the exactly module it loaded and use it in Mepis...
But google a bit or post more detail about your hardware. I've read all of your 4 posts and we know nothing about your hardware (is you sound card onboard?) or the other thread asking about your monitor refreshing without saying which monitor you have