I decided to incorporate Amir's EQ into Oratory's plot of the HD598SE (on the same rig as Amir) and
drew a (very amateuristic) approximation of what you may have heard.
View attachment 138300
Based on the blue trace I would describe the resulting sound as.
Better subbass, no more boomy lower mids but tight bass, much more clarity and forward sound more intelligible voices and instruments and better treble. The increased 1.5kHz will add to the sense of better imaging (lets call this the Grado effect but sans the sharp treble
)
I don' t think you're wrong preferring this over the stock sound but would recommend you also give oratory's EQ a chance.
You may not like it as much but that may be preference in your case.
You can now, based on the blue line change the EQ and see if it improves a bit more