You are mistaken. His post was in response to people stating they felt the DT880 wasn´t able to get enough volume on an IPad/with FiioE17.
Also, on a sidenote, your post sounds like "I have not ever heard the E17 but I'm just going to assume more expensive amps sound better".
I have heard the E17. And I have also heard the DT880 600 with much better amps... so I know the difference is there.
Play anything with low bass and pretty much any amp less powerful than an O2 clips horribly. It's especially noticeable in movies.
You're mistaken if you think the Fiio E17 is enough to drive the DT880 600 to its full potential.