Portable, travel DAC

I've been listening to headphones from my laptop while traveling lately. it sounds pretty bad. there is a lot of hiss as well strange high pitched sounds when the computer completes various tasks.

I think an external USB DAC is the way to go (I already have a headphone amp). Headfi turned me on to this DAC from silverstone. Has anybody tried this hundred dollar thing? It almost seems like you can't go wrong for the price.

http://www.silverstonetek.com/products-eb01.htm