It is possible that with a AD700, the difference just aren't that stark. I don't know the AD700, but with the K701 the differences are plainly obvious, with a standard headphone jack it's a sibilant, congested piece of crap...
The other possibility is that you're not really used to critical listening yet. On one level you could say what isn't obvious isn't worth the money, but on the other hand, your definitions of obvious will change with time and experience.
So far, I think your descriptions of sound have been fairly general. Try describing sound specifically in terms of highs, mids and lows and compare them. Try comparing the wide and depth of the instruments and see if there's any difference. Place the instruments in your mind. Don't worry too much that someone else said you'll notice a huge, gigantic difference with the AD700, that is the inherent limitation of subjective opinion, your perception will be a bit different... For example, someone may say the difference between two amplifers is night and day, but to me, it will be subtle.