What they mean is a stereo audio master, not a multi-track one. Discmakers accept the following formats: * PMCD master (pre-mastered CD) * CD-R master * Digital Audio Tape (DAT) * 1610 or 1630 U-matic Tape * DDC * Mini Disc Makers DDP (or exabyte tape) * 1/2" or 1/4" Analog Tape Those are all audio formats. So what you need is to have a final stereo (two tracks) master in one of those formats. For you, the most useful choice is probably DAT or CDR, so just transfer your stereo mix to one of those supports. Bounce a stereo file to disc and use a CD burning app like Toast or Jam or MasterList or Waveburner to burn an audio CD.