Headphone Amplification And Better Sound Sans Sound Card

I've solved my gaming graphics issues, namely by choosing the parts I wanted rather than buying yet another "Media-Center"-style all-in-one unit that did everything, but not very well, I'm now in need of a solution to my present awful headphone sound quality. I have a generic Creative Labs Sound Blaster X-Fi Xtreme Audio card that is not very good, sound-wise, and, because it doesn't even include an optical out plug, goes unused. I purchased a refurbished Turtle Beach headset w/DSS decoder, and, while it works as advertised, the headphones are terrible for music. I've replaced the TB Headset with a much better-sounding Pyle set, and will buy some "real" headphones as soon as I've determined that the source itself is sending out a good-sounding signal.I've seen pro and con arguments about sound cards, like the Xonar series that have headphone amplification included. My issue with that is I am more concerned with the graphics for games, and I've built this system with SLI (another gtx580) in mind, and I do not see enough room under or in between the dual GPUs for proper installation of such huge sound cards, though I'm glad to have my ignorance in this area demonstrated. The anti-Sound card group seems to be gravitating towards a separate headphone amplifier, and I"ve seen them from the $20 dollar model included free with another headset I purchased, to the $1800 tube amps. I think I would like to either go this route, or purchase a home stereo receiver that can output the PC sound, thus having both satisfactory amplification for low-volume music listening( or ear-bleeding levels, if desired) and the ability to power speakers elsewhere. I guess what I'm asking is for some entry-level priced PC headphone amplifiers to start off with. I see countless rating comments for the FiiO series, and while the prices are certainly attractive, the fact that they're so low-priced also makes me leery of their actual amplification abilities while staying neutral in tone.