Rudi, I managed to do a -VERY- brief comparison between the AK100 & RWAK100. I tried on 2 ear/headphones - TG!334 and HD700. The TG!334 is quite easy to drive and the difference was largest on these IEMs. The upper bass and lower mids felt thin. Vocals sounded somewhat nasally. The imaging also sounded somewhat shallow or more 2D-ish. My RWAK100 (after 16 hrs burn-in so many more to go) felt more full and better imaging.
On the HD700 that has a higher impedance they sounded closer to each other but it's an open headphone in a departmental store so you'll have to take with a pinch of salt.
Other RWAK100 aspects so far :-
1) after 12 hrs burn-in, the DX100 still has a slight edge on soundstage, imaging, and general "fullness". Will continue burning in the RWAK100. The difference is not great. I had to listen hard to discern the difference. One person PMed me and I kept going back 'n forth as though I was fickle minded. However that's a good sign that the RWAK100 and DX100 is so close that it takes critical listening to hear the difference.
2) Disconnected from the charger 6 hrs ago and there's hardly a dent in the battery life!! It's been playing continuously either through my earphones or through my burn-in resistors (at full volume in this case).
3) No gapless - GRRR!!!
4) It's so small, I'm not used to going out with such a small yet audiophile level SQ - I feel naked.
5) The auto pause when yanking the headphone out is a blessing and curse. Blessing that I don't have to worry about the app running in the background requiring to be paused or killed. But a curse when doing side-by-side testing, yanking the earphone in 'n out means I have to play/pause/fast forward the tracks on either one player or the other.
6) Instantaneous UI (unlike the DX100...did I hit that pause or not?).
7) volume knob although easily hit doesn't really change volume so no problems there. But build-wise it feels "rocky".
8) brilliant that when I insert a new SD card, indexing doesn't take that long. And even if I don't want to, I can go to folder to play.
9) did I say I feel naked already?
I'd call 5 a blessing. I don't really care for the fast A/B type of comparing and rather get the independent takes on the music presentation instead of just the 'sound'. Once they're both in your possession for a bit, you'll naturally reach for one over the other. If it's only foe size, it counts as well as the the other isn't better enough to dissuade you.