Guys, you want to try them out than read some hearsay about which is analystical or warm, it all comes down to which sounds best to your ears, I will look into 600 someday, but given I was so satisfied with the 650, there was no motivation. My next stage is STAX Lambda, so I have no interest.
There are lots of components that goes into a headphone setup. The source, and the amp. 650 is sensitive to what you feed it, it's not as simple as some joe plugging it into some laptop or etc.. If you source it well, it will be very transparent. I feel HD800 more sensitive to what you source it with.
Edited by SilverEars - 2/2/14 at 8:13am