Okay, this IS odd. I just received the 2nd set of Flares Pro today and, side by side, the new ones sound metallic compared to the first set (which are a couple weeks old and have ~50 hours on them). It's pretty noticeable.
I'm going to let the second set break-in overnight (they arrived this morning and they have ~7 hours on them so far) and I'll continue the comparison.
I suggest contacting Flare Audio about this. They are definitely looking into this matter, not ignoring it or writing it off like some companies might. Flare Audio is doing a great job following up on things.
I'm going to be sending my pair back to Flare Audio for inspection. The FlaresPro is great in many ways, but if the set anyone has is really metallic sounding to where it makes listening difficult, I really don't think this is normal and should be looked at by Flare Audio to see what can be done about it.
If its a defect, then it probably can be fixed. I'm not so sure it is though, or rather it could be there is a tuning difference between sets, as I suspected with the HiFiMan RE-800, but at least with the FlaresPro, FlareAudio is investigating this issue on their iem.
Again, while it could be different, I'm suspecting there is an issue in the upper treble where FlareAudio tuned to produce the "live sound" and some sets may have this tuning right, while others may be just a bit off and too hot where this metallic sound is being produced in various levels, depending on the set.
I respect Flare Audio, especially making an iem as good as he FlaresPro is in other areas of the sound, but if it were my decision, I'd have the upper treble either completely flat, or under, then work on tuning the lower treble instead for that added spaciousness. Or have smaller peaks in the upper treble that are not extended.
The HiFiMan RE-00 I got from goodvibes has a peak in the upper treble that while it gets a bit forward, it doesn't interfere in the other sound, nor produce a fizz to the sound I blame on the extended nature of the upper treble the FlaresPro, or certain sets of the FlaresPro, overdoes.
Instead, the RE-00 concentrates more on the lower treble area I mentioned is a safer tuning from sibilance. A flat, neutral bass tuning through to the mids like the FlaresPro features or a lower inclining bass up to the mids like the RE-00 has, combined with an enhanced lower treble flattening out mid treble, then lowering out in the high treble really is the way to go, in my opinion.
It'll be interesting what results in this. I'm hoping after I send my set back to Flare Audio they can find out the exact specific problem, even if it differs from my theory, and can correct it somehow. If its an inevitable side effect in the live sound though, then Flare Audio mentioned they'll refund me on it.
Of course I'll accept that offer, but I'd still really like to have a FlaresPro that doesn't have this issue, and pushes the upper treble back a bit so that this doesn't happen. I'm leery of getting a current replacement though, rather have them find out the problem and correct it. Not sure that can happen though.