I have been using Sennheiser HD660s and can say that XD05+ drives it with ease. I can't see reason why it wouldn't do same with HD650. But yeah, let's throw some more shiit on the device that you haven't heard with your own ears or even seen with your own eyes.

Did Larry tuned it? Why did they give th the job after all his tuning failures?

98% IEMs that have BA drivers use tubes.