This post in another thread sums the HD800S up well. It's very resolving, which is what I also observed comparing to my LCD3's. I hear a lot more detail across the spectrum, and therefore, enjoy them more than the Audeze.
I've spent the last couple of days evaluating 4490 and Gumby using my headphone rig, and I seriously started to doubt my state of mind when I made the above comments because through my Valhalla / HD600 I was struggling to hear any notable difference between the 4490 and Gumby and even my existing Uberfrost! However I managed to borrow a pair of the newly released HD800S, and the difference between the DACs on my headphone rig was finally revealed.
Lesson to self: identifying the weakest link in your chain is crucial if you are trying to hear fine differences between DACs. In my case the weakest link was my HD600. A part of my wishes I'd never heard the HD800S, because now I KNOW what I'm missing out on!!!...