After a clean install of Windows 8 I was not able to have sound from external speakers connected to a docking station.
Install drivers from HP, reboot.
From the HP website I downloaded the drivers IDT Sound drivers but the installation return : Not a compatible Hardware.
Option 1 :
In device management / Sound Video and Game Controller I deleted the High Definition Audio
Inject a driver from softpedia,
In device management / Sound Video and Game Controller I deleted the High Definition Audio and try the installation of HP.
All is good.