Alright, so here is my story. I was introduced to the intriguing world of enthusiast computer's about 7-8 years ago and things have spiraled from there with the purchase of my first "gaming" PC to many purchases and upgrades in the past years. One of my favorite upgrades was getting an Auzentech X-Fi Prelude to send audio to my old Sennheiser PC-150 headset and Logitech X-530's(I know, very unimpressive audio hardware). After going from integrated audio, to an X-Fi Xtreme Gamer, and then to that Prelude, I have ever since been in the pursuit of something that truly brings me enjoyment when listening to audio through a PC(my primary source for all forms of audio: Movies, Music, TV, Games, etc.). I currently have a Creative X-Fi Titanium HD which is sending audio to my Onkyo Surround Sound which I plan to upgrade when I move somewhere that allows me to do so(apartments limit what you can do with surround sound). The card is also sending audio to my Sennheiser PC-360's. Now, as far as sound quality through the Titanium HD, I am pretty happy in that regard. The quality is noticeably better than my old Prelude(which I quit using due to the notorious Crackle/Pop Issue many experienced with that particular card), but I am just sick of using PCI sound card's in general. Interference is a big issue that I have experienced in multiple computers I have owned. Overclocking causes many issues with PCI sound cards, and frankly, I'm tired of dealing with it.
So, what am I looking to do you ask? Well, I am thinking about getting something external to handle my audio needs. As I previously mentioned, I send audio to an Onkyo Surround Sound and my Sennheiser PC-360's. I have future plans to get a custom surround setup that has HDMI audio capabilities so I can send audio through my video cards over HDMI to my surround sound and I may get another set of cans eventually(ATH-M50's or HD598/600s possibly). What I am wondering is what I should be looking at to handle audio to my Headphones.(The ability to send audio through this device to my surround sound receiver would be a plus). I have looked at a Fiio E17/E9 combo and a Creative Sound Blaster X-Fi HD Sound Card, but am uncertain which of these are a better option for me, or if either are for that matter? Knowing what my future plans are for my surround sound and possible headphone purchases, what should I be looking at for options?
I should probably add that positional audio for gaming is quite important to me but I am also a HUGE movie buff and listen to a fair amount of music(see profile for my music tastes).
Also, I am confused on how using an external sound card or dac/amp combo works. Do you just send audio through the onboard sound card or do you still need a sound card to send audio to the external unit(which would defeat what I'm trying to accomplish)?