It's closer to the 650s. They are cleaner with a punchier and more transparent sound . Little details in the music are popping out. Instruments and vocals sound a little better to me. I'm not blown away but still satisfied. It will appeal to anyone who likes the house sound but wants something with more energy. If you want neutral go with 600s. 650s are laid back up top. 660s are more dynamic. $500 is a little steep and some people may want to wait if they already own a 650. I will be keeping them. Anyone interested in a headphone under 1k should demo them.