Just want to share my experience. I am using a macbook/itunes to feed the new Arcam rDac via USB with lossless audio (redbook or higher). Without adding Amarra or Pure Music the result is already on par with my Arcam CD-player. But adding Amarra (2.0 mini demo version) makes a big, big difference. More detail and much more depth and broadness in soundstage. The real surprise to me was that Pure Music (demo also) didn't enhance the sound quality at all or not noticeable for me.
Alex