You might want to head onto head-fi.org, they're really helpful there. But, the first things they would ask are:
1)what headphones will you use?
2)what source?
3)how much $$ are you willing to spend?
But anyways, most people would wholeheartedly take the Total Airhead over the Airhead, as it has higher quality components.
Do they really improve the sound that much?
This ties back to your source. Depending on the quality of the head-out (and the headphones), there may not be a significant improvement. BUT, that's only an IF, chances are it WILL improve the sound. Again, this ties back to the headphones and the source you're using. But if all you're listening to are 128kbit mp3s, then you need not apply to any of this "audiophile" stuff
