slight update but i am now leaning towards returning the FiiO EM5. with the prime day discount and tax they came out to around $275.. the rolled off/veiled treble/upper frequencies and stuffy/closed feeling is a bit too much to overcome despite the great bass response for my library. i tried using the silicone rings and while it did open up a bit without sacrificing much bass quantity, the characteristic extension and rumble towards the lowest end is lost and it's just not the same. It sounds like an average bud that way. The highs are a bit rough/sharp sounding and then it becomes mostly midbass focused which I think you can find with better technicalities in buds a fraction of the price.
With full foams on, which still sound best to me because they leverage the shell's bass flute design thing the best, there are just too many compromises that it isn't worth it. With earbuds the main draw over IEMs for me is 1. openness 2. comfort. But because the EM5s don't sound very open to begin with I can just get a much better listening experience for the
same part of my library (warning: kpop) using an IEM like, IKKO OH10 with good bass and female vocal presentation (which is also very comfortable despite their heft). I don't think additional burn-in can help the EM5, but I will try my best to get some hours in before the return window end of July.
I will say though the cable on the FiiO EM5 is great. I would probably value that at $110 alone. I might just buy a silver FiiO cable and use it with the Smabat M2S Pro if it's as good as its made out to be.
edit: also slight annoyance about the EM5 is that the shell and cable terminations are not actually black or smoke black they're like a very deep grey/blue color. I'm not tryna collect blue earbuds
edit2: another good way to summarize the EM5 vs say, the Chaconne is with the EM5 you're listening to the band and there's a vocalist. With the Chaconne you're listening to the singer and they have a band supporting them. Instruments like drums, bass, and guitar outshine female vocals in the mix on the EM5. Chaconne definitely spotlight the singer. I want to say the EM5 do better with male vocals and everything sounds a bit more balanced. I don't feel like I need to turn up the volume to hear male vocals over instruments as much, but the effect of band-first/distant vocal presentation is still there. for example, EM5 beat Chaconne at some band-supported hip hop like
The Roots. Sure, the Chaconne has more vocal clarity but I don't think that's the most compelling part of music from The Roots. The EM5 fills everything out better and highlights the music's strengths rather than hampering them like they might do for a female vocal ballad
edit3: HMMMM yea EM5 slay at male vocal songs like
Giveon - Heartbreak Anniversary