Ok with that :
What's funny is that I don't believe this hobby is 'all subjective'
But there is not an
automatic correlation between high quality and high prices.
By the way, the tuning is the more important thing. Then, it all depends on what we are looking for.
Me :
1) homogeneity,
2) balance,
3) no systematism... (sound colouration, specialized tunings or other things like that... : No go...)
4) large dynamic scale AND nuances
5) tones
Balance is not that simple
Musicians call something balanced if it reproduces the original instrument as close as absolutely possible.
Most audiophiles consider something balanced based on how it measures, completely unrelated to how it actually sounds.
A few of the most balanced IEM that exist like the IER-M9 or the TG355 are considered warm and bassy by audiophiles because they were tuned by musicians and PA engeneers with real instruments and sounds as reference.
They don't just call them IEM because they think it's a cool word, they are actually monitors and they use them for monitoring.
What most audiophiles call balanced is completely unusable for monitoring due to the recessed bass and pushed upper mids.
If you would use them for monitoring, the result would sound weird and off as the sound you hear is far from the actual sound the instrument products.
There is quiet a difference between actual IEM and what audiophiles call IEM and what audiophiles call balanced and what musicians call balanced.
So if you use the word balanced, there is actually a need to state your background if this is just an hobby or if you're actually an musician.
Because for real IEM, there is a price limit until it doesn't get better, for audiophile IEM, there is no price limit as it's all a matter of taste