You could stretch the headband. It will lessen the clamp. Really improved comfort for me. No more sore ears.

Ultrasone Pro 550 w/ He-400 pleather pads   Bass is decreased ever so slightly. Might be due to improper seal. treble is increased. Nothing dramatic but sibilance may occur. Soundstage is increased. This is a big plus for me. Comfort is Beyer level if you don't mind the headband...

The thing that originally turned me away from the K70x was the lack in the lower end. These might be more satisfactory. However, I already own a pair of He-400s and I'm afraid it'll be more of a side upgrade than an actual upgrade.

The He-400 is open. They won't isolate at all making them terrible for portable use. What kind of music do you listen to?

I'm about to pull the trigger on a pair of these headphones. Just one question: Would the Fiio e11 be a good match for them?

Sony xb700.   I later traded them for a pair of broken xb500s I could play around with. Much more fun.

The DT770's aren't what I'd call portable. The large ear-cups and 10 feet cord ensures that. It's possible to use them as portables but not entirely problem free. If you go this route I'd recommend installing a removable cable. Just be careful and if you can, get someone experienced to help you...

The DT770 250ohm are slightly more neutral than the 80ohm version, not to mention, harder to drive. They aren't exactly portable, either. The Sony XB series has some pretty crazy bass but, IMO, this is the only thing they do well.