Unless there is a good reason, I'll generally stick to desktop amp when it comes to full size >= 250ohm. Tube amp doesn't necessary measure / performance better than solid state, but often is a lot more fun to listen to, plus tube rolling to get the best synergy is in itself great fun as well. The end result can be very satisfying. However, HD600/650 isn't that hard to drive that portable can't drive them well enough. Leckerton Audio UHA-6 MK2 will be something I would consider as a portable all-in-one solution.
I Should note my source would be the Mac Book and Mog music service Kbps 320 would that change your view. I don't listen at
high volume. My Hd 650 will be delivered soon as well as a E11 which I ordered for a HD 598 which I returned. Maybe I will try the E11 with my Samsung galaxy 3 and my GR07 at the gym because it gets pretty noisy so the E 11 may help. At home it's nice and quiet and the Mac Book gives me plenty of power so I just need a nice simple solution to enjoy the HD650. I'm for some reason attracted to the E12 but I respect your work. I could leave a desk top system in my living room where I sit but if feasible something I could carry around in the house with my Mac Book would be nice but of course I want a good experience. Also do I need a Dac included with the MacBook. Thanks.