Colors, depth,pop are due to the W900's Triluminous feature. As for using the Advanced Contrast Enhancer? I don't use it on my HX850 due to there is no need for it in my book so its off. The W900 is a good tv no doubt but in my opinion the blacks are not as good as the HX850 and on top of it it don't have the Gorilla Glass/Opticontrast Panel combo which to my eye produces the most beautiful PQ I have seen next to Sony's 4K TV's. The only advantage I see in the W900 is the Triluminous feature which if you really compare the 2 TV's side by side you don't see much difference color wise. That's the only slight advantage the W900 has over the HX850.
Lol. I know you LOVE your set. I did, too. And I already stipulated in my quick review that the 850 has better blacks. But I also have had the 2 sets in my family room, side by side, after having set up both properly. They are different sets, so whereas the Advanced Contrast Enhancer might have negative effects on one, it may not have it on the other. I stand by everything I wrote, including my conclusion.