I have bought some shure SRH840 headphones. To my understanding they do not NEED to be amped but they can benifit from it. And also, I'm sure I'll need one later on. My question is what would you recommend? It will most likely be attached to an Ipod touch 4th generation. Price, well... thats the problem. I really don't want to spend much at all. I would looooovvveee to spend under $40. But i know that can be a bit tough. Really more than anything I need to be educated on what I need. Thank you very much for any help given!