Remove the foam in front of the drivers. They won't turn into the HD668b/SR850 in clarity, but they get clear enough to really notice the little details in the recordings (and the frequency response gets a lot more balanced, too)... not that clear as to strain your ears after an hour of listening like the superluxes and the samson. I like how my SR850 sounds, but I find listening to the HTF600 for prolonged times much easier. Take out that foam, you won't regret it.
After doing that give your ears and brain some time to adapt to these headphones.. you'll probably love the signature of the pannies if you come from the HD668b and its siblings. At least that was my personal experience.
Remove the blue area, that's the foam which ruins these headphones. Remove the green area if you like, there won't be a difference in sound quality. You know, I was about to replace the foam with stretched pantyhose as you are going to do but I forgot about it
... that's an excellent idea, that will definitely keep dust and hair out of the drivers without impacting sound quality. Mine have been for two months without foam and protection.. no issues so far.
I can't stress it enough for everyone else who finds these headphones lacking in clarity and detail/too rolled off in the mids/highs..
REMOVE THE FOAM! You'll thank me later.