I've owned the HD650 and sold them quickly. They sounded very veiled to me. From what I've read, if you really like the HD600 you would not like the HD650. I had the HD650 a year ago and I have the HD598 now. Auditory memory is not real good but I believe I like the HD598 better than the HD650. Of course you can cover yourself by buying the HD650 and selling the one that you like the least. Its not likely to cost you a lot.