I just demoed the HD700 today with a FiiO E9 (not sure of the DAC). I did not really like them, the highs sounded harsh and the music seemed to lack seperation. Vocals also sounded a bit too warm for my taste. Do you think this is to do with the amp used? I also demoed the Beyerdynamic T90 using the same setup and they sounded quite superb.
I used this exact combo this weekend and can tell you that, without a doubt, it's a very bad combination. The E9 is just a bad amp to use with any bright can, IMO (although I haven't heard the T90 on them). With the HD 700, my observations were exactly the same as yours. Harsh treble. No separation. Very forward vocals. It's a shame because the HD 700 has some of the best separation and imaging out there as well as an amazing vocal presentation.
My recommendation is...
- don't come to a judgement using an E9, E09K or any other Fiio product on the HD 700
- more than any other can I have experienced in the past, the HD 700 gets better with break-in (although I'm sure your demo copy may be ok)