It's said the stax X9000 & BHSE system is nothing less than Senheiser Orpheus by the Chief engineer and CEO of Moondrop who will release their new electrostatic headphone in the upcoming 2022 Shenzhen Audio Show.
Accordingly, Stax/BHSE system is more controlled and introverted with low profile highs while Orpheus is more aggressive.
That is very reassuring to hear. I really need to hear an HE90 at some point...