After struggling a while with all the options and old/new drivers, I wasn't still that happy with the sound of the Phoebus.
So I decide to give my system a new clean Windows 7 install, and now it sounds AWESOME!! The sound is crystal clear and very powerful, I even don't need the higher gain option anymore for my 50ohm headset.
So this is what i did:
-First make sure the bios version is up to date.
-than DISABLE the ONBOARD sound card in the bios.
-Install Windows 7, and get ALL the Windows update's FIRST.
-Than install the correct chipset, sata, network and video drivers. Do NOT install the ONBOARD audio driver!!!
-At last install the Phoebus with the latest BETA version 188.8.131.52
-Now the system is complete up and running and the sound is really amazing!! Very detailed, clear and powerful!
(Don't use Dolby HT and all the other surround crap, when you have a good surround set or some good headphone's!)
(Only mismatch I got is in Internet Explorer 9, with Adobe Flash Player 11 (11.3.300.271) It's playing stereo sound like multichannel sound!)