Woohoo, never mind.
I used Foobar2000 to apply ReplayGain on every song, and since stupid iTunes couldn't recognize the change in any of the song files' tags, I restored my iPod (aka wiped it clean), re-filed all my songs onto the iPod, turned on Hardware EQ w/ ReplayGain on (no clipping enabled), and...w00t! Deep bass w/o showing any distortion, as far as I can tell.
Dear gawd, screw getting another amp. This EQ makes the PA2V2 shine to my K701s like never before. And I'm still using this through my headphone out! Imagine this on a line-out...

EDIT: Never mind, just tried heavy techno and it went bad again...
FURTHER EDIT: Excellent, I finally got around to following through with Febs' educated guess, and it works.