It won't. How everything is supposed to sound in terms of soundstage, where the positioning is of instruments etc. is all information that is stored in the audio file(s). That information just needs to get to your headphones with a sufficiently strong, clean signal to get the best result.
It's important to realize your motherboard's audio already functions as a headphone dac/amp combo. So you are already amping. Any dac that has an output stage is already amping. Now what matters is that the DAC and amp can keep the signal clean while sending it to your headphones, and that they can do it with enough power, to make sure the signal your headphones receive in analog form is relatively identical to the information in digital form that was stored in the music file. The job of an amp is not to change this information, or to add anything (nonsense like clarity, resolving power, etc.), but to increase current and voltage delivered to the headphones in case the signal lacks strength. When the signal lacks strength, it will cause a lack of volume, clipping, and noticeable distortion (in the bass and treble most notably).
Assuming you have good onboard audio (and it seems you have) that is powerful enough, this most likely will be quite well taken care of, in which case even more amping will do absolutely nothing for you. In fact, it might only damage the signal.
Edited by SunshineReggae - 8/3/14 at 8:14pm