the audio format on CD is usually referred to as "CDDA" see : http://en.wikipedia.org/wiki/Compact_Disc_Digital_Audio

CD rippers like dBpoweramp or EAC will extract to WAV format losslessly(and then encode to FLAC or MP3 etc). I remember reading that Sooloos will rip a CD as a single large FLAC format file, with CUE file to provide track metadata.

My Sonos plays back in PCM format, 44.1kHz. through coax SPDIF . My music files are ripped as separate FLAC files using dBpoweramp. The Sonos decodes FLAC "on the fly" and produces PCM/WAV which outputs to processor. The FLAC format was designed to be able to be decoded quickly even on slow devices. Encoding is another story ...

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