I'm pretty sure I ordered the black pleather ones, I don't recall there being such a selection when I got mine.
That said, I didn't notice any real difference in sound, they were bass shy with the stock pads and are bass shy with
these, seal has never been an issue for me that I can tell despite having glasses and a lot of hair.
I use an EQ to slightly, only slighty, up the bass and all is well.
Much like every single other human being to comment on the sound of a headphone, I seem to have had a different
experience than others. Ain't diversity grand?
I don't recall them being troublesome to fit and they were the first set of pads I've ever changed.
The K550 are almost annoyingly good for the money, it's hard to find a real upgrade without either going open
back or spending a hell of a lot of money.