I picked up a HD 8XX for less than half the price. They sounded quite bad at first but after EQing them, they sound amazing. I did not expect to like them so much after reading how many people think the bass is lacking and that it has a boring sound. Might be my new favorite headphones.
Try some other ear tips or adjust how far you have the ear tips pushed in.
You can also try EQing other points in the 5-10khz range, the location of the sibilance can vary depending on a number of factors.
I think they’re considered around the same level but with the caveat that the HE6SE V2 needs a capable amp to drive it. Personally I drive mine to more than loud enough levels with a $150 AMP/DAC combo.
Based on the reviews, these are supposed to be competitive with TOTL models like Focal Utopia, Audeze LCD-5, Hifiman Susvara, etc. Josh and DMS explicitly stated that they prefer these to the LCD-5. DMS even compared these to the HE-1 which are nearly 20x the price. $3000 is out of the budget of 99%+ of people but for the types who spend ridiculous amounts, these will probably be interesting.
http://abx.digitalfeed.net/
If you really want to prove it, you can post your results for this ABX test