I received mine today as well. So I'll just post a few quick out of the box impressions since gelocks have pretty much nailed everything I hear right now. It's been a while since I owned the 840s, and also a couple of months since the last time I listened to the 1840s. But right off the bat I will say it sounds like a much more refined 840 with more bass quantity(and quality) with better extension at both ends. For me it has more in common sonically with the 840 than the 1840. So it's more of an evolution in that direction.
The bass is just a little bloated, and the highs are slightly subdued. But I will say the extension is there in the highs which is a good thing. The mids are fantastic...rich, full-bodied, and lush. There is just a slight hint of grain though. The bass extends deep, has good texture, and definition and fairly tight as well. I'm hoping the slight bloat, and I mean slight, goes away with burn in as well as the slight grain.
But these are a very fun sounding set of cans. They have just enough of the technicalities to please even the most seasoned headfier, while being musically pleasing to listen to. I think these easily surpass the 1840. Instrument separation isn't quiet as good, but plenty good enough. Hopefully that will improve with burn in as well.