Amp Suggestions.

[bengold]

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.
 
Any suggestions?

 

[Mad Max]

Save up $200-300 for a really good portable amp/DAC, then your ER4's will truly come to life. 

 
You won't miss anything special skipping out on $100 "starters."

 

[Croozer]

For less than $200 you can get a FiiO E7/E9 combo, it will give you the versatility of having a portable and a desktop amp in one package and it makes plenty power.