Don't think we heard the same thing. While soundstage is really a forte of EX600, clarity of the Yamahas is excellent in my opinion, especially in the mids (unless the seal was not good enough).
What can confuse people is the super-airy treble on the EX600/EX1000 (quite the trademark of these Sonys) associated with mids less present than on the Yamahas. This is the easiest trick in the book to achieve a sense of super-clarity, you can even recreate this on most IEMs by using a strong V-shape EQ. Emptying the mids will give an impression of reinforced clarity.
I actually enjoy the super-airy treble of the EX600. It's very pleasing and entertaining. Not a fan of EQ though (like I never use the digital zoom of camera). Warn you though I am not an audiophile or with trained ears. I was still using the Apple buds one month ago.