There is bug in ALSA for some chipsets: speakers do not mute when headphones are plugged in. There is patch from vendor available at http://www.linuxant.com/alsa-driver/ Problem is that patch is for package alsa-driver, but in gentoo it is hard masked and one usually uses kernel alsa modules. Please, incorporate this patch into kernel modules. Reproducible: Always
We only carry patches that are either submitted upstream from Linus' dev tree or at least are in an official linux staging tree. http://dev.gentoo.org/~mpagano/genpatches/faq.htm If this patch get's submitted upstream, we will review at that time for possible inclusion.
I am marking this as invalid instead as I just realized that I used wrong option (selected another chipset), all works fine with right one. Sorry my bad.