So finally some impressions from me heh
For the past two weeks I'm listening to HD800 exclusively, I needed a month to adapt to the different sound signature of 800s. At first I was very annoyed about the lack of bass they have compared to HD600 (and some people say HD600 don't have enough bass already) but now I don't miss it, there's plenty now, its tight but not as deep as HD600. I understand why Sennheiser would want to reduce bass, in my opinion because everything else is now more forward sounding, more open, vocals wouldn't be as realistic as they are with more bass impact.
I have to repeat I don't miss any bass and I have tried them with variety of music. They work great even with bass heavy Trance and Electronica. R&B sound fantastic as well and my favourite Jazz is jaw dropping.
Some say HD800 are bright headphones but I disagree, they are however very detailed and certainly not veiled in anyway like the HD600. I have to admit vocals were never so close to reality before and soundstage is just amazing with HD800. Its like music is floating in my cans.
The first thing I noticed when I put them on my head is how much heavier they were compared to HD600 which are my reference cans. They aren't too heavy just heavier, noticeable. I used to say HD555s were the most comfy cans. Well I have a new reference when it comes to comfortability. These are huge and my ears don't even touch the cans.
The pads don't seem to be velour and are of much high quality and more skin friendly-they don't itch. Build quality is decent but in time the build flaws become apparent. The cable is very nicely build, don't know how many strands it has but its twisted and I don't see myself buying a new one unless I go balanced someday but that doesn't seem to happen any time soon since I enjoy them a lot with my current setup.
My setup is as follows: ND-S1 dock (which is the most neutral transport I have ever heard besides my Yamaha S-1000 cd transport) then the setup continues in either DacMagic with RA PSU>Auditor or Audio GD Ref5>LD IV SE.
I mostly use the 1st setup as its much more musical but the Ref5 has the detail. Interesting how some components just don't have synergy. LD IV with DM is grainy while REf5 and Auditor are harsh with HD800.
HD800 need a nice stand as they are very fragile cans. What more can I say, people who listen to them are jaw-dropping and I, myself now enjoy these fully. Are they worth the money? No, hugely overpriced, HD600 offer much more value at 1/5 of its price (Europe) but I don't imagine my setup without them (HD800). :)