Headphone output doesn't work as expected. When headphones are connected internal speakers are muted but there's no signal routed to headphone jack.
However osstest produces some cranking when playing through /dev/oss/oss_hdaudio0/pcm1 (audio engine 1): HD Audio play center/LFE and even expected test melody when it reaches /dev/oss/oss_hdaudio0/pcm2 (audio engine 2): HD Audio play rear.
On this system there are two silver jacks for line-in and mic (despite ossxmix claims they are pink and blue) and one black headphone jack (this one is combined with mini-TOSLINK S/PDIF output). Chipset is nVidia MCP51.