Fiio FD7
Caveat: These impressions are based off the limited time I've been able to devote to the FD7 over the past few days and are of course subject to my own preferences, biases etc.
For the last few days I've had these generously on loan from
@tgx78. The first thing one notices is a tremendous sense of air, spaciousness & clarity top. There is a nice sense of "3dness" to the headspace and detail & nuance just jump out at you. These excel in terms of technicalities & resolution, at least in the top half of the FR. Female vocals are lush, natural and seductive. Another plus for me is that the upper mids/lower treble, though perhaps bordering on being a bit too crisp/vibrant at times are never fatiguing, shouty or anything like that.
Where this set doesn't quite work for me is in the lower half of the FR. While there is a tremendous amount of detail/clarity/resolution etc. up top I feel it achieves this by selling short the lower mids & bass at times-- I often found myself craving more density, dynamics, body & extension down low. Where female vocals were wonderful on the FD7, male vocals were pushed back a wee bit. Jumping over to the Oriolus Reborn, by no means a bassy earphone, and one which I tend to EQ the mid-bass up and the upper mids down, I find it nonetheless has a much more satisfying native sub-bass response than the FD7. The net result of this is that, while in terms of raw detail & resolution up top the FD7 is indeed comparable to something like the Elysium but imho the signature is too cold and clinical on the whole and for me lacks the vibrance, vitality and organic je-ne-sais quoi of Elysium's sound. The top end feels very present and clear, but it doesn't quite have the life & breath that Ely had up top and the emotive pull of the sound as a whole. I would also say that it doesn't have the warmth and emotive factor of something like the Oriolus Isabellae though it likely does excel that IEM in terms of raw technicalities. When I put the Isabellae in my ears for the first time I was immediately swept off my feet and couldn't wait to look through my library to find all sorts of stuff to try-- while the FD7 is certainly impressive it did not give me a similar experience. More clinical is probably the best way to describe it and I'm someone whose bias is strongly towards the emotive. YMMV, and all that.
In a nutshell: there is greatness here, but the signature is too skewed towards the upper half of the FR for me and on the whole didn't give me the sort of emotional engagement I crave with an earphone. It's interesting that I often associate emotional connection with DDs intrinsically but my experience with the FD7 on this front was almost completely the opposite with the Audiosense DT600, which has 6 BAs and no DD at all.
These impressions were based off my listening library which includes a lot of Dire Straits, CCR, mid-bass heavy techno, Morcheeba etc. and does not contain a lot of classical, string instruments etc. so take that for what it's worth.