Hey guys, I'm currently at college and only have access to my laptop and its mediocre onboard audio. I have a pair of Sennheiser HD 555s, and they don't sound nearly as nice as they do on my desktop. I'm looking for recommendations on what I can do to get improved audio quality. A number of people have suggested external DACs, so what do you guys recommend? Are there any other methods to get improved quality? Budget is ~$100 US (more if necessary).