I like the bass of the X1's; I like their musical warmth
as contrasted with the still somewhat clinical nature of
the K712's. I like their slightly larger soundstage - not
as large as the K702's or Q701's, but larger than the
The K712's have more clarity, more pinpoint accuracy,
and possibly more treble extension (though this does
not translate into "sparkle" for some reason).
I like also that the X1's can be driven pretty nicely
with a decent portable amp.
Also, it will be a little more time before I can tighten up
this comparison further. They're both very good headphones
and I need to do a lot more listening to them.