I finally decided to contact chaintech USA and TW and I got an answer from Taiwan HQ !!!
I really appreciated their quick responce and actually I am going to stick with their products! I have to agree ASUS is top also!
So here is their answer!
"
Dear Spiro,
Thanks for your interest in our product. Here are the reasons CHAINTECH uses Cmedia in stead of nVidia APU. 7NJS ZENITH is designed to incorporate Cmedia 8738 as an external bridge through PCI interface and it?s a hardware decoding and consumes less system resources. It?s similar as any other audio CODEC but with additional 5.1-channel and SPDIF for digital surround output equals to what Dolby surround would offer. Soundstorm's spirit is to enable the 5.1 channel audio which provided by Cmedia also. Moreover, Cmedia privides both SPDIF in/out but NVIDIA APU can only support SPDIF out. Cmedia is very experienced in designing audio chipset and the skill is very
matured which you do not need to worry! As a motherboard manufacturer, we know what is actually better to recommend to our users!
Hope I answer your questions and clear your doubt!
Let me know if you have other questions!
Best regards,
B. Lin
"