Think of it as a sound-card, it has to be connected to a computer, and will act as the sound-card of the computer.
As soon as you disconnect it from a computer, it can't do anything, furthermore, it has no audio inputs.
With the line-out, you can connect it to a cmoy or or Fiio amp, but the built-in amp is so good I see no point in doing that.
I haven't listened to the line-out properly yet, but I'll connect the LO to my stereo later.
wait, It has a build in amp? then dont they promote it as DAC + Amp? they never said a thing in the web about an amp