Audinst Hud-mx2 no sound?

Hi,

I bought a Audinst Hud-mx2, i plug to Rasperry pi and Volumio Beta
in the web gui it shows a model name of Mx2 but no sound.

(Audinst Hud-mx2 Uses Via VT1728A Usd and PCM1796 (Texas Instruments) Chip.

Any idea?