HD600-serie is really tuned for music enjoyment and not accurate sound.
What "audiophiles" call as warm sound means inaccurate reproduction with weaker treble/upper mids.
Which is bad thing for sound positioning of binaural sound.
Stereo content like music simply fail to give a damn about accuracy, but binaural cues are very sensitive for that.
We hear in 3D with only two ears, because shape of the head causes direction dependant changes to signal received by both ears from sound source.
Brain simply processes location of sound source from those differences.
And those binaural cues rely heavily on frequencies where typical "warm" headphones are inaccurate/weaker.
If you want absolutely maximal details like foot steps fair £100 level AKG K702 is one of the best.
It wasn't designed for any "audiophile" fashion sound, but for neutral and accurate sound monitoring usage.
Of course neutral bass isn't exactly big on "fun factor".
So if you want also some strength in bass others are better.
But that better bass punch shouldn't come at expense of lopsided frequency response.
With no real headphone amplifier and low end DAC worser than in sub £40 Audigy Fx/Xonar DGX don't see Sennheiser GSX as sensible buy.
Sound BlasterX G6 is lot cheaper and comes with proper headphone amplifier and DAC.
https://www.overclockers.co.uk/crea...-sound-card-pc-ps4-xbox-switch-sc-107-cl.html
Even £100 for GSX wouldn't be balanced with it being no good as headphone amp or DAC.
Something like £70-80 would be more like its real value for the hardware.
As for positional accuracy of HRTF Sennheiser GSX is definitely good, but overal looses to Creative's HRTF for my head shape.
Because shape of the head and pinnae differ between people, there's simply no single HRTF which would be accurate or even somewhat good for all.
It's all up to how close/far listener's head shape happens to be to who knows how chosen average head shape model used by HRTF algorithm.
And if head shape is farther from average, immersion can worsen fast with directions becoming ambiguous.
For accounting different head shapes Creative's recently released Sound Blaster X3 has advantage over anything else by including Super X-Fi named head shape customizable HRTF tech.
You basically take photos of your face and ears and it analyzes those for customizing HRTF to better match your personal binaural cues.
With operation of human's binaural hearing being long known basic physics, it's crazy how there haven't been anything similar in use for years.
Compared to graphics game sounds are really still in year 2K.
Or really even behind that partially:
Instead of being able to get original true 3D sound data of game with actual sound source locations around player, sound cards have nowadays access only to lossy and flattened into plane 5.1/7.1 sound.
(which also lacks proper distance information besides missing vertical data)