I've already browsed hundreds of pages on Head-Fi and got swamped in information. Does anyone here use a portable amp for their Shure E5Cs? I find that the sound quality is nowhere near its potential from the line out or headphone out of my iRiver compared to my GSP Solo on my Hi-Fi. I'm comparing them to the Koss KSC-35 I also use on my iRiver and they sound very similar directly connected to the iRiver. So I think I might need a mini amp to improve its potential.