Nice, the Vita actually has a Wolfson DAC (PSP had one too) so with the right pair of headphones , you will get some glorious sound on the go.
Quite a varied list of music there. The M-Audio Studiophile Q40s would make a good rec, but you sacrifice on portability and they really do need an amp to shine.
For unamped portables in the price range, again the Phiaton MS400s are a good fit. I also second the V-Moda M80s. Neither of these cans require an amp and are compact, light and relatively comfortable. The former sounds warmer and isolates better. The latter have more extention, a wider soundstage and are more durable.