> Can you hear faint cymbal hits in the background now for instance

Of course my long time using that pair of headphones has given me more than enough time to really get used to their exact sound signature but yeah, it's easier to pull out details like that on those than it would be on the X5's for example (which weren't made with that in mind). I haven't listened to the M50x's enough to tell.

> How many centimeters or meters were added?

Many. I've just swapped between the M50x's and the 770's a couple times writing this comment, and I can say with certainty that the 770's have a much wider soundstage.

With the M50x's, you can hear that you are listening to music with speaker drivers mere millimetres from your ears. With the 770's, you have the illusion of centimetres, and it sounds like the music is coming from all directions into your ears, rather than being localised to one spot. Hope that makes sense.