Right on. That was what I was assuming regarding the HD650, and hearing you confirm that makes my want to buy and try significantly less. Are there any other engaging cans you would recommend, open or closed that are a little easier to drive? I currently have an HD 25, M-Audio Q40, and Meze 99 Neo (Should have got the Classics). They all manage to keep me rocking in a good way. I've purchased and returned close to 3X that many cans, and got a little burnt out on the buy and try madness method lol
Have you tried any Grado offerings? If not they might be worth a shot. I haven't heard any of the "new" e-series myself though, only the older ones.
Another option to look into could be the HD660S but unfortunately I haven't heard those either.
Personally I find the Fidelio X2's to be a really fun pair of headphones but maybe you've tried those already? They're also easy to drive....