OK. It seems like you know exactly what you want based on your knowledge and requirements, so why ask here? You know the price point and performance you are looking for, what to buy, and where to buy, so just do it, then tell us what you decided and why, and if it meets your expectations.
As for the headphones, I’m curious as to whether anyone has actually found such a combination of attributes. It likely exists, but one might have to go though hundreds of products to find it.
As for the EQ programs, I an interested in what others may have found or suggest. For example, it turns out Equalizer-APO actually DOES have parametric filter capability, if a bit clunky. But it took a while and me sort of stumbling on to it, to find it. I posted sort of hoping someone had a quicker answer.
And... For the most part it’s been a fun discussion.