i wonder how will planar sound with just a thin porous mesh,
Still block the airflow if you meant by kind of nylon / paper dampers because the porosity still too tight.
This will made the bass section bloated.
The best i can think of is damper made of foam that shaped like tiny cylinder with little holes on center of it, imagine donut shaped medium density foam, but longer in length
2-4khz are tamed by blockage, means anything block the entire nozzle will tame this range, whatever the materials, thicker or tighter materials will tame more
While the material itself is affecting different kind of frequencies.
High density foam (sold as imported sony foam in ali, but the truth they are different from sony foam damper inside many sony IEMs which are not as high in density) tame more higher trebles, think of 8khz above with absorption of decay quite much. The decay is too soon to gone, kill the extension and sound unnatural to me.
The medium density of is the best from my experience as they absorb the decay or unwanted ringing or resonance by just nice to clear sibilance while keeping sound quite natural
Soft density foam acting as blockage only and just made little effect to absorb the unwanted resonance.
The nylon or paper damper more affecting high mids and presence region 2-5khz, while making only little different to upper treble part.
Best solution? Tune the IEM better, just give damper to absorb unwanted resonance with kind of my idea damper, that will let the airflow go through freely, hence we got clear, air feeling bass as opposed to bloated bass because of the blockage.