Like others have said the x9k isn’t an evolution of the 007 it is it’s own thing. If you gotta compare it than say it’s the next step of the 009. It takes the ability to really dig into recordings and it takes the presentation back a little.If it "came for free", I would gladly accept that as being objectively better.
However, for me, there is an inherent byproduct with this type of "microscopic" presentation. Not only is is even more "directly" revealing, but also lighter, more ethereal, which I consider to be not a good thing on a lot of recordings. I do not like the idea of choosing recordings that are suited to this type of presentation (where musicality plays second fiddle after clarity and detail), it should not work that way, I would rather have less of this for the sake of being less picky.
I guess there was already a big "split" regarding the 007 vs 009, maybe fans of the latter might like this further progression, but I think Stax could do some more tweaking, which is odd to think about, when the price is already this high up.
I also do not know the definition of 'more precise imaging', if for me a stage and imaging in a headphone is always artificial, and it is only subjective which one is more to a listener's taste (depending on how the recording was made, e.g. minimally-miked, multi-channel, etc.)
The separation in the X9000 is certainly even stronger than before. But strong to a point, where it can "slice" the recording to pieces, and that's not a good thing, e.g. not superior in my book.
Same with the speed, faster in the X9000, but is it better? Not necessarily, this lightspeed can feel a bit spiky at times, which is a lot more annoying than having less speed but none of this weirdness.
When listening in complete darkness, the 007 can do several things the X9000 cannot.
Slower meaning less ethereal (which is better for me)
Has less width and air but more depth 3D and cohesiveness
More impact (in the treble as well, not just in bass)
And it has a "defined, more characterful" tone, which is not nearly as dry e.g. not as troublesome to match with other components.
Also works much better at low volumes, e.g. a bit more protective against hearing damage, I found the volume adjustment on the X9000 'more tricky'.
Only the bass is a big flaw to me and a big question mark regarding amping or other possible earpad-related mods (I also do not like the fit very much, although it may get improved soon)
While I cannot point any big particular flaw in the X9000 the same way as I can with the 007, it just sounds weird on a lot of occasions next to it.
It’s not recessed. The detail is all there. But the presentation has you back a bit. And this is in no way a bad or negative imo.
I’m trying to understand your past couple posts. I disagree with about 40% of what I’m reading. It’s got the speed it’s got bass it’s got the analytic features. The attack and decay of Stax is there. The bass is great on these. I A B them with 007 and there isn’t a decisive winner in the bass department.
Driver is 20% larger than 009. It’s delivering everything effortlessly to these ears.