Hi
I have two pcs with two different mobos 
One gigabyte Gaming 3 the other Gaming gt
One has realtek sound the other sb recon3di
The cheapest one with the realtek, has an incredible sound with the same headphones that  when I try the Gaming GT, which has incredible low volume, and much MUCH less "punch"
Either the 3 exagerates sound or the GT is too quiet. 
Tried drivers, Windows settings, nothing gets GT nowhere near Gaming 3.
Or is it just sb < realtek? GT had advertised one of the Best onboard sounds.
Sorry for my rusty english