Just got my D1 today. Shipped 28th, arrives 30th, can't complain about that at all. Audioengine site recommends 40-50 hours burn-in so I'm going with initial impressions. For fairness, I have consumed several alcoholic beverages.
In easy to digest list form:
1. Seems very loud. By seems, I mean the volume dial in the lowest area of the dial is silent and then the sound cuts in abruptly. I suspect that in actuality, they just don't operate well or at all for very quiet listening
2. Using the USB causes many pops during use. I unplugged all other USB devices and went straight in without any hubs; still an unsettling amount of popping, almost a ticking sound
3. Optical works flawlessly
4. If I peg the dial at 100%, I get listenable volume from my DT990 600 Ohm. Initial opinion is that it sounds way, way better than my E9, but we'll see what sobriety does to that tomorrow
5. Unexpectedly, my Shure SRH840 show a lot of sibilance. That does not occur using the E9, E11, Turtlebeach Earforce or unamped.
6. Grado SR225 sibilance was increased slightly, though I was pleasantly surprised to hear bass in some songs; not the forte of these cans and this is best bass I've coaxed out of them yet
I'll be paying attention to see if the sibilance smooths out, and will also troubleshoot the living hell out of those USB pops.
HeadphoneAddict, thanks for your great post. It was a major help in making my choice. I recall you also had some noise issues using USB until you bypassed the hub. Do you have any other suggestions for the issue, as I seem to be facing it as well.