I doubt you'll find an IEM that benefits significantly from that amp unless the Colorfly is a poor source to start with. Your post doesn't mention the type of sound you're looking for so I'll just say that I think the FX700 is generally better than the MG7 if you don't need isolation. Haven't tried the H-200.
Thanks for the answer. Unfortunately FXZ700 has that lack of isolation that some mention and also a slightly short cable, which could be a problem for me as I'm quite tall. Still, I didn't cut them from my list
I don't know how to define the type of sound I prefer, but I think it's something warm, slightly v shaped. At home I have Beyerdynamic DT990 (which are known for bass+treble and details) and I enjoy them a lot! Of course, they are open headphones and don't have that punch. JVC FXZ700 seem to be quite similar to those (which is good).
I'm not really sure about Atrio MG7 as they are already a few years old and I'm thinking new IEMs should have better technologies and should be improved. Of course, this might be just a gimmick or my snob logic :). But I would rather buy an IEM which was recently launched vs an old one.