I believe the AZ has 24 bit dacs rather than the 20 bit dacs in the AR version. AZ model was never sold in the USA much to my consternation. My suggestion is to go with a 24 bit DAC like the Cambridge or Benchmark. The Denon DCD-1650AR is a terrific transport and driving a 24 bit DAC makes the most sense. My opinion: skip the AZ.