Thanks a lot, so now AKG K712 PRO, HiFiMan HE-400i are out of the discussion.
Now I need some comments on the Audeze EL-8C, as per some reviews they are as good or better than HD600 and they are planar (this is what looks attractive on paper). Also, they are pretty much in similar price bracket:
* Audeze EL-8 Closed (new): ₹53k
* Audeze EL-8 Closed/Open (refurb): ₹29k
* Beyerdynamic DT 1990 PRO: ₹50k
If EL-8C is worth it then the refurb will be the one to buy, it's from a trusted source so can't really go wrong with the quality there.
Haven't heard the DT-1990 yet but I do have the HE400i, HE560, EL-8 open, HD650 + a few others and had the K712 (sold) and HD600 (sold) + a few others. The EL-8 is not neutral if one considers the HD600 neutral, it improves on the HD600 with bass that goes deeper, mids a bit more forward and highs that have a nice sparkle but not sibilant like the HD600 was for me. I've replaced the HD600 with a DIY Ypsilon S1 driver build at first but have changed over to the Ypsilon R1 since its more extended in the bass and treble and has a very nice balanced sound to me.