A good link for DAC basics? (PCM vs. DSD, De-emphasis,...)

[GD3]

I've been toying with the idea of building my first DAC. Upon researching the Cirrus web site, I understand that the main components are a digital audio reciever (takes S/PDIF or AES converts it to serial data and clocking info) and tha DAC itself.

The CS4398 accepts PCM (in the form of serial data as described above) and DSD inputs.

What is DSD and where am I likely to find a DSD data source?

My Dennon CDP has a coax RCA digital out. Can I assume this is 16 bit S/PDIF ? left or right justified?

And what is the deal with de-emphasis? I always thought it was automatically selected per data on the CD. Should it ALWAYS be on for red book 16/44 ??