Separate names with a comma.
Up for opinions
I have both RE0 and RE-ZERO, and they are pretty good for/with classical and baroque music, but in the end, most of the time I end up using HiSound Wooduo 2. They have very sweet and pleasant treble, not too recessed mids, and absolutely wonderful bass extension - perfectly controlled and very very pleasant. For cello music, can't be beat.
I also have Klipsch X10,S4, Vsonic GR07, Vsonic VCD02, Hifiman RE01 and few other IEMs, where only GR07 gets some playtime with classical music alongside RE0 and Wooduo2.
Just to clarify (@OP), you are looking for an IEM that's good with classical music AND compliments the FA-003, correct? May I also assume that you would like a neutral signature, or are you just about open to anything that, in our respective opinions, we find good for classical music? It would profoundly aid the search for your ideal IEM.
HiFiMan RE400, MEElectronics A161P (or Fischer Audio equivalent). Only two I can think of without saying the word Etymotic... Whoops.
EDIT: Brainwavz B2
My biggest issue with the FA-003 is the closed soundstage. Not surprising considering it is closed. BUT, I do prefer a more on-stage SS, as that's how I'm used to listening to orchestra music. (I'm in a orchestra)
So between the:
Fischer Audio DBA-02 MKII
Phonak Audeo PFE 012 + extra gray and black filters
Phonak Audeo PFE 112 (are the accessories worth the extra 40EU?)
What suits my needs best? I would consider myself a analytical listener. Can't seem to find Brainwavz B2 in stock anywhere.
Btw, I don't mind earbuds as well, perhaps the Yuin PK2 or Sunrise Audio Dragon2?
Lowered my budget.
Phonak Audeo PFE 012 with gray tips
From most expensive to least. I have small ear canals.
My vote still stands by the RE400. The most neutral and flat out of the budget, but if you wanted to stretch it a bit the R50 and B2 (DBA-02) would be great for the analytical signature.