[tranhieu]

Don't know if this's the right place to ask, but well, I don't know anywhere else to go, diyaudio is too somewhere-above for me...
Anyways, I've looked at several iem's internal while opening their shells and in most cases they only consist of some resistors with filter caps. So my question is is there any benefit going more advanced than that? Is it because of the lack of space that those xos can't get any more simpler or those manufacturers are just being lazy?
Thanks for reading

 

[nikongod]

The best way is actually by going for SIMPLER IEM's with single drivers, but sssssh, dont tell anyone - its kind of a secret. 
 
When a single driver adequately reproduces the desired frequency range, using a single driver in favor of multiple drivers will reduce (eliminate) the likelihood of creation of phase smears & funky shifts at the non-existent crossover points. This is a lot like the razor-blade wars - A straight razor STILL shaves better than any safety razor, yet we have 5 and 6 blade razors.
 
If you had a little more room, a more complicated crossover would probably work better than a simpler one. The same goes for using better quality caps in the same circuit. OTOH, you can do a lot with simple first order crossovers and you dont need anything but the ETY-ER4p and the linkwitz labs thingy anyways.
 
Link to linkwitz labs earphone tweak