Dell Studio 1749 NO headphone sound

[Francesco Bolzoni]

Hi all.
I own a studio 1749. All works fine but i can't able to get sound from
headphone.
The soundcard on the sistem is Card: HDA Intel, Chip: IDT 92HD73C1X5 as
reported by alsamixer.

I do this step:
- plug headphone into both headphone out of pc
- "play" with sound preferences tool, setting output alternatively to
"analog speaker", "analog output" and "analog headphone".
- "play" with alsmixer.

No way to get sound from headphone.
Someone can help me ?

thanks