Yep...he's got enough juice for the DT880 600 ohm so the 770 shouldn't be a problem.   I got my E11 yesterday btw. For anyone who is planning on using it with customs: be aware. The hissing is pretty loud with my JH5s. I wouldn't call it a good choice for sensitive IEMs (although it's a really great amp for its price). But that's OK for me, i mainly wanted it for driving my K701 with a Dr. DAC nano when I'm on the road with my laptop.