I received my DACport just a few days ago and am very happy with it. The convenience is hard to beat: it plugs right in between my Mac (MacMini and MacBook) and my Grado's, and substantially improves the sound quality. I have so far used it with my Grado's (325is), AKG K702, and K271, and it drives all of them well without any apparent limitations.  I have tried it so far in comparison with a Peachtree Nova, where it can hold it's own. I don't think I can tell a substantial difference one way or the other, and am quite impressed by the DACport...