Because I thought more space between the ears and driver would make soundstage bigger. But like u said and its true pads do make huge difference , but again why they destroy the sound on HD6 series ? I read on forums that a lot of people use for example Dekonis on DT1990 and fix some spikes on highs, Or HD800 . Did they make such a perfect tuning on HD6 series that is now way to make it better ?
My experience - the Dekoni Fenestrated Sheepskin sounds great on the 660S. I prefer them to stock pads. Maybe the Drop pads are of much lower quality and design than the Dekonis? I found that with the Dekonis I agree with what is said here:
https://dekoniaudio.com/frequency-response-curve-new-dekoni-sennheiser-hd600-pads/