The aqvox has made the W5000 midrange heat much more tolerable. I listened to them for a straight three hours solid tonight at low to moderate volume through the Dynahi and experienced zero fatigue. This is good, I might end up keeping these cans.
Pretty much my impressions two posts above stand. Smaller soundstage then the 999es, but that smaller soundstage is filled with a very tidy laid back sound that is wholly realistic and natural, with none of the treble hardness that is forever present in the Sony. Its still digital, but it is a smooth digital. A hell of a fucking deal for $750. At that price point, I would heartily recommend it to anyone looking for a USB DAC.
But then again, I'm listening to an SACD on the 999es and it is magical. So as it stands now I have to keep both, at least until I get a great deal on a Cary CD 306.