x3. Although I listen to the HD800 at lower volumes than what I used to listen the HD650, but that is because I found the 650 sounded quite a bit better at mid to high level volumes.
If anything I find the 800 transparent, not bright. But if one is used to the 650, the 800 might seem bright (in the same system).
x4 for me too...and they are the most comfortable headphone I've ever had on my head to boot.