I'm going to build a PC in a couple months and i need help deciding if a sound card is worth it. I'll be using Turtle Beach X41s (yeah i know they're old, but i love them and i already own them). The motherboard i'll be using is the Gigabyte 990FX UD7 with Realtek ALC889 onboard audio and i'll be using the optical out to connect it to the headset receiver. I'm needing to know if something like an Asus Xonar DX (or even better, an Essence STX) will improve sound quality at all, or if it would be better to just use on-board audio. I'll probably be listening to music and watching movies and stuff on my system as well.