Will I notice an increase in audio performance with a headphone amp?

I use Bose QC 15 headphones (contrary to popular beliefe, they work fine and do an excellent job of cancelling noise), but I'm not entirely sure I will notice a huge increase in performance using a headphone amp on my laptop. I do notice that my iPad sounds worlds better than my laptop (and iPod touch for that matter) and would like to get that sort of performance from my laptop, but am not sure I will notice a significant increase in performance. I was looking at the Nuforce Icon Mobile so I can use it with my iPod and laptop, but the Nuforce uDAC-2 also looks very tempting... are they worth the $100 price tag?