Hardware :: Internal Speakers Don't Mute On FSC Amilo Pro / Resolve This?

I'm using Linux Mint 8, kernel 2.6.31-12 (and I tried several other distributions and had the exact same problem) on my FSC Amilo Pro 3525, where I have Intel HDA (ICH7) and Realtek 883. My problem is that when I plug in my external speakers, they do not mute the internal ones.

I've searched and searched the forums and came up with a half-baked solution where in alsamixer I - almost - mute front, and bring master to maximum, and in that way I hear the internal speakers just a little.. and the external ones play at maybe 1/3 of their normal volume. Every time I reboot I have to do this again. I can't mute front entirely because then it mutes all sound.

I tried adding various options to alsa-conf, which seems to be a fairly often suggested solution, including the one where I identify the model of my notebook, and it did not help.

Now. When I tried to find the answer, I came across several tutorials that suggested adjusting options in volume control, etc, inlcuding jacksense, that I found I don't have listed.

Being pretty ignorant about Linux, I came to the conclusion that it might be Pulseaudio that's causing the problem. For instance, alsamixergui shows Pulseaudio as card. I did try preventing Pulseaudio from loading, did not help.