So, it has come to my attention that I should probably get a portable amp to use with my headphones and my computer. I typically use a pair of Etymotic ER-4Ps with my MacBook Pro and iPhone. The sound quality has never bothered me that much because of they super isolation provided by the Etymotics and also because I try to keep only high bit rate tracks in my music library.
I'm wondering what a good starter amp would be. I don't really want to spend a lot of money, but I would like actually be able to notice some difference. I don't even mind buying a used amp. I've heard that the Nuforce Icon Mobile is a good starter amp, but I was looking for other options as well.