EDIT: sorry, I thought you were looking for a portable solution. I didn't read the op with enough care. As you seem to own a big rig for home, my reply doesn't apply to you.
Anyway, it was...
***
I'll give you my take.
The iMod will be surely superior, theorically. The iMod with Stax SRS-005 trashes any other mp3 player in clarity and sound separation.
Anyway, if you are going for the iMod, you are not planning to use a Stax setup in the first place (and would be better set with a DIY dac, like the Alien or the upcoming Gamma1, for stationary listening).
For real life, I mean portable items, you are not going to enjoy the iMod Vcap quality: current portable amps suck in my opion. By this, I mean that they don't deserve their price tags quality wise over the integrated amps most good mp3 players. Also, 99% of IEMs (all universal IEMs, probably) aren't going to improve like a Stax setup would.
If you plan on carrying an Audiocats-modded SR-001 MkII electrostatic setup (portable amp + headphones), I'd suggest you to get the iMod. Anyway, the lack of isolation of such setup would make things useless again. Otherwise, for IEM purpose (and with current portable amps), the iMod is an useless choice. This is why I sold mine.
Sorry if I am trumping your expectations, but you wanted a honest reply, and this is what I can tell you, without making it more pleasant than it should be.
Go for the Sony.