Thanks for the info and advice shigzeo! I don't like amp
I don't take clarity as of bumped highs. And I like the way SM3 sounds, laid-back treble. In my opinion, non-fatigue traits of SM3 is not only because of their laid-back treble, but also the neutrality (overall not too cold nor too warm, not too bright nor too dark), and good accuracy in producing vocals (to my ears vocal comes from SM3 is very similar to real life).
I have added another criteria in my definition of fatigue. Phones of dark and over-smooth presentation. Listening to FX700 and I felt uncomfortable after some 30 minutes. No, it is not the soundstage which is choking me, since the soundstage is pretty big. FX700 doesn't have any sign of unpleasant highs to drill treble hole on your eardrums (extract from your review ^^). But I feel hard to breath. The same applies to the Radius DDM.
I start to think that the reason SM3 is universally (as of 25th June 2010) accepted as great IEMs not only because they are technically superior to others (by technical I mean instrument separation and 3D presentation). The neutrality and accuracy of SM3 is very gentle to the ears. The airy presentation of SM3 is another strong factor. If
CK10 is bright and FX700 is dark, SM3 stand in the middle.
Provided you found the right tips for SM3 of course.
I am waiting for a remolded UE10Pro and let's see how custom works on me before I jump into the big boys group