Thanks for all of your help. I now have the X3 working now with a few albums playing. My first impression is that the amp section does not compare to my O2D. But then I should not expect this. I am expecting to find it better than my iPod. I see it can power my 300-ohm DT880s.
I will spend some time checking it out. Next will be a search for headphones. I am thinking about the models of Audio Technica or Senheiser below the $200 mark that has low input impedance.