A few people mentioned the ZDAC and I disagree with that recommendation. I picked one up for $300 a while back and sold it after a few months. It was replaced by an Arcam irDAC which I purchased off Ebay for $409 (there was a seller in Italy who sold a bunch of them at that price). The irDAC smokes the ZDAC and there's no comparison. If you're looking for something you will simply enjoy listening to, consider a MHDT Paradisea+.
I found the ZDAC to be too bright on the high end.
I found the ZDAC to be too bright on the high end.