I heard the HD800s recently and have to admit that it is an excellent sounding headphonoe and deserve all the praise. However, I do feel that the R10 do sound sweeter and has more organic & fluid presentation. OTOH, the HD800 might present a little bit more air, details and seperation of instrument albeit a bit dry in presentation, but at the end of the day I just prefer the R10. I'm hoping that I will get a chance to compare the two in a better and more quite environment to have better conclusion.