Sweet just found one new for $195. ( I prefer to by all my electronics new it just feels right that way. lol)
Objective 2 Headphone Amplifier.
AKG Q701 Reference Headphones Quincy Jones Signature Line
sounds frickin awesome
can I put a stamp on that guys or is there anything else I'm not realizing?
You'll want a dual RCA to single 3.5mm connector as well, to go from the STX into the line in of the O2.
Something like this from whatever retailer you choose.
Make sure your PSU has a free molex power, as that is necessary for the STX.
Other than that, you're set!
Good audio makes a world of difference, and I'm glad you're getting into it.
Something to keep in mind, make sure your source material (the music files themselves) are in good quality. Look for MP3 320kbps or above if possible. No amount of gear in the world can fix a crappy recording.