ok i got my RE0's through in the post, and apologies i got my numbers wrong. they are indeed 64ohm.
after about 30 hours of burn in the bass has gotten better than i had expected. not bassy, definately below what i would consider balanced, but not unpleasent. maybe a bass booster like the E5 would be nice, but ive not heard one personally.
i have a 5th gen ipod classic 80GB as my source, and i also have an ibasso D10. the ibasso doesnt add £200 worth of SQ improvement over the ipod. it adds a little more bass depth and quantity, a little more treble extension and clarity, and brings the mids forward slightly, but honestly i think the ipod 5th gen has a decent enough inbuilt amp.
the cost/benefit ratio of adding an amp to the ipod classic for these phones just isnt worth it IMHO.