It's the 250 Ohms version.  The more I think I about the more I'd like to have it portable.  The cMoyBB looks pretty good, would you say that's a better fit for me than the E11 then?

I just picked up the Beyerdynamics DT 880s.  I need an amp to drive them to use its full potential.  What kind should I be looking for?  I don't need it to be fully portable but it would be a nice plus.  Looking at spending a max of $100