Its safer and will give you volume and tone controls.
ie
When you plug/unplug the ipod, without a limiting volume controller, the thump could harm the speakers.
If you play something with the volume set really high by accident, it can cause damage without a limiting volume control.
If connecting to a PC through an external DAC, you can use Foobar2000 and its volume control (64bit float internally) for high quality playback with no pre-amp.
