For a small portable amp in a tin you can't do any better than the JDS LABS cmoy. Ok it's slightly more expensive then some of the competition but the circuitry is professionally assembled and the overall quality of parts used is great. I opted for the 18v option and choose to replace the stock op amp with a AD8066 unit which suits my grado sr325is very well. I know the grados do not need to extra juice but this comes in handy when using different cans as well. Coupled with my Grados for a little portable system the sound is great and well balanced...