Nope we can't, and it was proposed that we humans are not that sensitive when it comes to phase either (haven't read a detailed research on this though).
One well known problem of balanced armature is that the phase curve isn't linear across the spectrum and as most people know IEMs that implement BAs tech always possess in-the-head imaging, which IMO is the result of not having linear phase. Google sound localization or IPD/ITD or ILD for more info on this.
Some companies like UE, JH approach this problem by hacking/modifying the inside of the drivers via working with manufacturers (Sonions/Knowles). Their final products are pretty neat but there's still more room for improvements. Or you can use dynamic drivers instead like what AKG did with ther K3003.
In speaker world phase alignment has more to do with fine tuning the response curve by neutralizing peaks and notches. But with IEMs that's not the real issue at hands since we have other means to dampen the curve.
Edited by tranhieu - 4/15/13 at 7:18am