Recently my grandmother bought me a pair of Grado SR325is as a surprise. I will mainly be using these headphones in study hall and at home. I am in need of an amp that I can just put in my suitcase or backpack and take along. I was looking at the Grado RA1 but I am not sure if it is necessarily portable. Im in a $350 budget. Any suggestions? Is the RA1 a good match for the 325is'? Is it "portable"?