Well, I wouldn't put it in such a general way. Here are many people who don't agree with you, including me. I cannot say anything about the SR xx Grados and, as you can easily check, I didn't.
But I can prove that my Grados don't benefit. There is very little difference between the iPod sound and a Black Cube Linear, who delivers all the current that you ask for. An OTL tube amp like the earmax, who should be bad delivering current, is also not worth its money, if you run Grados RS-x.
That may not be true for the SR series, though.
Grados own amp is even battery powerd. If you open it, you find cheap stuff, hardly more than you will find in an iPod. This may mean that even Grado itself doesn't believe what you seem to know.
Edited by mironathetin - 11/21/12 at 7:47am