I am looking for a new IEM for my OTG system (DX50 / iBasso P4). My musical tastes extend to classical (esp. Shostakovich and Wagner) and jazz. My favourite full size cans (both driven by the Audio-gd SA-31SE) are the HE-500 (open) and DT48E (sealed).
I currently have a number of IEMs, but have issues with all of them:
GR07 - great soundstage but grainy and slightly sibilant treble, and they are terribly uncomfortable (more than 5 mins is impossible)
Ety HF5 - excellent detail and clarity, but little bass and no soundstage. Also, I dislike IEMs which require deep insertion.
Shure SE425 - good soundstage and resolution, but sound a little "soft" and "slow". Midrange timbre could be better. Same comfort issues as the Etys.
FAD Adagio III - the best soundstage, almost like full-size open cans. Very comfortable due to shallow insertion. Issues, however, with bass bloat, a recessed midrange and a searing treble. Also, isolation could be better (high frequencies are not attenuated).
I will be travelling to Tokyo for a brief vacation in October, and am considering either the FX850 or the FAD Heaven c. Which of these is more likely to be what I am looking for? What should I expect to pay in a bricks-and-mortar store such as e-Earphone?
Finally, would the FX850s provide enough isolation to use in-flight (this is not critical, I'm just interested to know).