Sorry that I have to answer you a question again ;p.
To be honest, they sound very similar on instant listening. Both has great bass, imaging, clarity and neutralness.
Compared with 1+2, NT6 sounds slightly more mid forward with smoother lower treble region providing a very well balanced vocal presentations (upper vocal can be a little bit hot depending on the songs). NT6 has a slightly lifted mid high area (9k-11k Hz) which generate super combination of clarity and resolution without going too hot.
1+2 on the other hand has a lifted upper mid/lower treble region (4k-8k Hz) leading to superior soundstage width and pin point imaging. Treble extension on both IEMs are about the same, so I would say they are equally clear, just with different type of clarity. If you want more clarity,detail and brightness in vocal, I would say 1+2 is better, if you want ultimate clarity with everything, especially in instruments, NT6 maybe 5% clearer (which is the brightest I can accept).
Like I said before, they sound more similar than different.
NT6 is clear whatever you pair it, but I would recommend you pair it with something that has great treble extension. With rolled off upper treble like ak120 or 901 will actually make NT6 sounds harsh/less smooth and too forward.