James, thanks for the comparisons! I was wondering if you would agree or disagree with the following:
Based on my k3003 review and memory, I remember the k3003 having more upper mid presence than the 1+2, so vocals on the k3003 were slightly more forward and sweeter sounding. But the 1+2 midrange, while more distant, seems more linear to me providing more transparency and detailing.
I also remember the k3003 treble being brassier and weightier than the 1+2 but this could be due to the triple flange tips I used. So the 1+2 seems even a little airier and grander in soundstage.
I agree on the bass differences you mentioned. I also think the faster and harder edged 1+2 bass probably gives some a better feeling of coherence, since coherence in these instances is being used to describe the sound of the different driver types, rather than a suckout or timing issue that some multi-ba's have. Regardless it didn't bother me in the least on either the k3003 or 1+2, although I've been accused of trying to minimize others opinions on this (oh the incredulity and outrage!).
Mids: that 's a hard question... I tried to EQ the 1plus2's mids to match the K3003 and it took only 2-3db for female vocals to achieve equal presence (I don't use tone generators). Going by Rin's K3003 graph that shows the AKG's upper mids slightly below target response, I wouldn't conclude that the 1plus2 are more transparent. But honestly, the difference being very small and taking spatiality into account, any interpretation of one sounding slightly more transparent than the other is fine with me.
As for detail, I actually thought the K3003's TWFKs were ever so slightly more resolving and refined, but again the difference was very minor and most noticeable only during cymbal decay in track #2. I heard no noteworthy difference in treble noteweight though.
The difference in bass also turned out smaller than expected, as I found the 1plus2's harder edge was only partly due to faster transients and partly due to more deep bass punch. If the K3003 were really significantly slower, it would have shown with track #7.
Btw, if you want to compare them side by side for yourself, I can get my K3003s to you sometime. Though, on second thought, it's entirely possible that you may not be able to hear them at their best with the triflanges.
Like shotgunshane said, it depends on your ear anatomy. I'd think that smaller outer ears are more problematic with the 1plus2, and smaller canals more problematic with the K3003.