I'm using mine with an Oppo 103D feeding the new Vanity Pro. The Alpha DAC 3 is my first DAC, I've been using a Marantz SA10.
I have a fairly high end two channel system and I've always preferred analog. My dealer, Galen Carol Audio, thought the Berkeley might be the one to convert me to digital. He was right. Massed strings on Bruno Walter recordings, always a problem, now sound far less edgy. Not quite RCA strings, but close and more than acceptable. The tell is I'm listening to more and more digital.
The Alpha DAC 3 is a fantastic product and I cannot recommend it enough.