I have an X68 motherboard by Gigabyte, onboard audio is ok (used to use it for desktop speakers) but Creative products are a noticeable step up. I've heard rumblings that the Sony MDR-1 is a competitively well-performing headphone in it's segment, but I haven't read a review on it yet (share your thoughts?).
Mad mentions several good sub-$200 options in his guide here (1st page), and ones that sound best with good amping are noted as such in the reviews. One of the most recent good headphones has been mentioned by Mad on pretty much every page of this thread since he got it several months ago: Sony MDR-MA900. Read up on it in the guide, and read the whole guide while you're at it, it's a great resource to make your own conclusions from to answer your questions.
Edit: PurpleAngel beat me to responding
He mentioned already having a random soundcard... Chances are it's about as good as the Xonar. If the Creative soundcard is broken though, the Xonar DG is a good starting place, also the Creative online store (fulfillment by Amazon) is having a 30% off sale till the 22nd using coupon code 30GIFT13
Yeah I mean I haven't read many in depth reviews of the MDR1s, I might add I would really want a closed rather than open headphone, otherwise I would probably own the MA900 already because it seems amazing :D I just really don't want sound leakage. Also I've heard people say that a soundcard really isn't necessary or sometimes harmful to audio, I have no clue what basis that's on, same people said best thing is just to plug your headphones into a simple external dac/amp and call it a day. That being said I really like Creative's new technologies, so I wouldn't be strictly opposed to buying one of their soundcards (SoundBlaster Z? It's just the ZxR without all the fluff I don't want) and plugging in a good headphone/headset into, the issue with that is that it takes up a PCIe slot, and that would mean on a future computer build I would kind of have to not go Mini-ITX as to have at least 1 extra slot besides my graphics card to support the card....
Really appreciate the help guys, audio is a very ambiguous domain so I'm just being open minded as much as I can lol
Summary: Is the best thing to plug an AMP into the onboard sound or USB and run headphones through that?
EDIT: Ok so the soundcard lying around my closet is a Xi-Fi Titanium from 2007. I'll see if it still works but since it came with my alienware desktop I can probably get a replacement for it under warranty since I got that extended warranty like 4 years ago haha
Edited by DrunkenTiger - 12/20/13 at 10:36am