I now it will not improve my headphones performance, but there is a noticeable difference between my laptop's sound card and the Fiio. Unfortunately it is all I have for now, and can't afford anything else for the moment . It will have to do the job until I save some extra money.
When the time comes, I will post back to ask for ideas.
I think you misunderstood Chris. I don't want to speak for him, but I am pretty sure I know what he means. The E07, despite it's fairly low cost and all that, is pretty damn awesome. You might get a touch more headroom elsewhere, a tiny bit more current, and maybe a better DAC, but you won't find THAT big of an improvement going to a better amp. Fiio makes pretty great stuff, especially for the cost. About the best you can do for Grados is a good DAC, a tiny bit of gain, and a unity-gain buffer. That's exactly what the E07 is. Could you find something warm and tubey, or with a bit more headroom, or with a bit more current? Probably. Will you notice any real difference? Probably not.
Chris swears by the O2, and nwavguy (the designer of the O2) has pretty much demonstrated that it's only marginally better than the E07.
Edited by scootsit - 2/5/13 at 7:16pm