I think that you might have better luck with this question on Head-Fi. A couple questions that come to mind. Do you need the amp and headphones and digital player to be portable? Do you need your headphones to block out noise? When you say a DAC reading from an external hard drive, do you mean without any computer involved? Do you have tube vs solid state preferences on the amp?
For $2k you can put together a great headphone set-up.
For $2k you can put together a great headphone set-up.