Yea 009 is still king in that regard.
I have reasons to suspect that the new QA FLOAT electrostatics may be even better and more transparent than the Stax 009.
I still own a pair of the original Jecklin Float electrostatic headphones and they were in their day imho the most transparent headphones on the market.
I bought the HE1000 V2 as my new travelling headphones and have modified my camerapack to accomodate them. But good as they are I don't think they are quite as transparent as the best electrostatic headphones.
Nor the Utopias .
I listen to electrostatic speakers at home and to my ears no,absolutely no, traditional box speakers I have heard,and I have heard many of the very best ones,are quite as transparent as electrostats in the important midrange and treble regions.
I have auditioned Focal's speakers and they are very good indeed being box speakers but electrostats, they are not.
One of my first reactions to the Utopia with some of my reference tracks was that they sounded very similar to their most expensive speakers , but like those ,a wee bit hard and very upfront in the midrange with some tracks.
Almost as if an intentional presence lift which was definitely not there live,nor in my master files,has been applied.
Once again saying you need to listen to acoustic music to really hear what comes closest to live music.
With every other genre with amplified instruments and synths and such all you are doing is comparing which flavour of already inherent distortion you prefer.