As I wrote before, I have quite a lot of experience with dynamic cans. I own the HD800, the S, the 650, the 600, the Utopia... The HD800S on my OTL amp is one of my absolute favourite setups of all time. Dynamic drivers in full size cans are very resolving, but not necessarily the last word in terms of visceral impact. They'll show you everything, especially something like the HD800 or Utopia, but they lack that heart-stopping punch on a HE6. On the other hand a planar like the HE6 will show you much less, drawing not in pencil detail but in flashes of oil-based Pollock. The W900 hues much closer to the traditional strengths of a dynamic driver. The W500 felt like it was going for the HE6 type impact- big, bold. Combine this with the BA drivers in there and I can definitely hear why some people felt the bass was flowing in slow-motion. Everything is relative. Just like, relative to a BA driver, the W500's dynamic bass driver felt like the king of the abyss. But pair a big, bold dynamic with a lightning quick BA as in the W500 and of course you'll hear a difference. It's tastefully done in the W500, though. One of my good friends likes the W500 with his EDM, which is more of the Paul van Dyke variety, and he's perfectly fine with the W500's speed. That's not wrong. It suits his music great. Which brings me to this: ultimately it depends a lot on what genres you listen to. If you like to listen to something more complex with lots going on like jazz (plenty of low-level detail needed to recreate that atmosphere), orchestral (complex) and well-mastered EDM, you'll probably like the W900 a lot better. If you just want something guilty, something big, bold and beautiful, something like a never-ending cheat day, then the W500 is for you. The two IEMs are really not successors to one another at all. In the sense that the W900 is an evolution of AAW's quest to get more out of dynamic drivers and improve the coherency in a hybrid, then yes, it is a successor. But if you're expecting a W500v2, then just stick to the one you've got- you won't find it here.