astro A40 do i use ther right?

[abuomlak]

i have astro a40 and my motherboard is g1 sniper 3 i use the optical output but do i need to buy sound card or the optical in my motherboard is good enough because i have been hearing that i need a sound card that support dobly digital live and i been told that with out the dolby digital live sound card i dont get the real 7.1 and i have the mixamp
thank you

 

[abuomlak]

do you know one that its good because i don't know allot about sound card
thank you
and is will there be different that is worth buy the sound card