I just got mine. I tested them with a few songs in the OFF position. I found them flat in terms of balance, and that they have a somewhat veiled sound; surprisingly pleasing. Clear but not bright or harsh.
But in the ON position, WHAT A DIFFERENCE! The minute details pop out and the aural image widens and deepens. I did find the on-board amp very noisy, but for $80, they're a bargain sound-wise.
EDIT: They instantly reminded me of my Denon AH-D340, but I really disliked the sound signature of those, and gifted them away.