I'm trying to setup stereo mixer which is available and turned on, however generally when doing this the microphone is muted in speakers and you need to unmute that (I've done this for a lot of computers), but unfortunately for the current computer no slider exists for the microphone. I've tried registry fixes and using drivers straight off RealTek's site (instead of HP's, it's a HP p6110f) but nothing works.
I've heard of a simular issue that was fixed by unloading all audio drivers, then allowing Windows to set its driver up first. Then the audio driver from HP loaded next. The slider returns. Seems its dependant to the windows driver to be installed first and then the audio feature driver loaded last. These features are usually supported with system "hooks" to allow the HP driver to see the current access profile. Without the hooks in place, the features are basic without any extended ones visable to the HP driver.