Well the 7hz Zero:2 arrived yesterday, I have been listening for a while now and I think I found my new daily driver (no EQ needed) it is really well balanced with the perfect amount of bass and treble for me, I didn't like the original version it lacked bass and was a little bit bright and fatiguing but this one is perfect.
I also tryed both the KZ Castor, The Harman version (first two switches on and 350 mesh) is somewhat similar to the Zero:2 but a bit brighter and also lacks some bass for my taste, The Bass version (third switch on and 350 mesh) is obviusly bassier but some of the detail in the mids is obscured by the bass and it is not as clear as the Harman version or the Zero:2, also they are big and heavy but comfortable. The Harman version is not as eficient as the other two.