Bro when i'm connecting the headphone with Logitec G510S keyboard which has inbuilt audio controller,i'm getting proper audio with mic,so there is no problem in headphone.Also headphone works properly with inbuilt realtek audio manager driver.
And i am having logitec Z906 surround sound speaker system & i am connecting through SPDIF(Optical cable),the speaker delivers excellent audio with this Xonar DX audio card.
My concern is this card is working fine with speakers but why not working for headphones??