i found a soundcard PCI version which has the specs to compete with the XOnar Essence ST
it uses a AK4396 dac chip as compared to the texas instruments pCM chip as the asus
the AK 4396 is also the same chip used in the very popular Emu 404 USB external SC and DAC
check out the link
HT Omega - Claro halo XT
the price is about 200$ on newegg but i heard it can be had in 180
50$ extra for the daughter board thou
it uses a AK4396 dac chip as compared to the texas instruments pCM chip as the asus
the AK 4396 is also the same chip used in the very popular Emu 404 USB external SC and DAC
check out the link
HT Omega - Claro halo XT
the price is about 200$ on newegg but i heard it can be had in 180
50$ extra for the daughter board thou