Compared the iPhone 4 to my desktop system (high end) with the HD 800. They sound the same, pretty much. dynamics slightly better on the M1HPA maybe. Bass a bit more powerful on the iPhone but it's really just minor details. iPhone drives the HD 800 without ANY problem at loudest volume (best anyway, since its digital volume control) it sounds like high end hifi.
Trust me, if you have an iphone (wish I didn't sold mine), don't spend your money on a portable amp unless you're using very tough to drive cans. Not really necessary.
This surprised me, and I know many will go:
"Ofc a phone can't match a high end desktop rig!"
"It's to cheap to be that good"
"Its so small, HOW?"
"It's not even a dedicated audiophile product!"
"Blasphemi to use a high end headphone with a phone!"
Blabla, these people need to be more open minded. Just look at measurements if you don't believe me!