Forth Order Noise Shaping?.........

I saw the phrase "forth order noise shaping" in a product description for a Marantz 320 pro cd player and I'm curious.

What is it? What does it do? Is it a marketing term to confuse people like me? Have any of you heard the cd player in question?

I have not heard of the pro CD player you allude to but....

"Fourth order noise shaping" refers to the sigma-delta DAC that it appears to be using.
The term "noise shaping" is used for a class of DACs called over-sampled data converters (the other class of DACs is called Nyquist data converters). In over-sampled data converters, we use certain feedback & feed-forward to design what is called a noise transfer function (or NTF) which describes how the noise of the DAC is shaped at the output. In over-sampling converters we shape the noise in a high-pass fashion. Intuitively, this shoves the noise from the in-band (20Hz-20KHz) to the out-of-band (>20KHz). The total noise energy does not change (entropy) rather it is moved from one area of the freq. spectrum to another.
The high-pass function is described by what is called an "order". So, here Marantz has a 4th order delta-sigma DAC that creates a 4th order (24dB/octave) high-pass NTF.
Depending on what their sampling frequency is, a 4th order NTF will yield a 20 or 24 bit equivalent DAC. Delta-Sigma data converters are basically non-linear circuits but with today's advanced CMOS fabrication technology are very simple to manuf. Over-sampled data converters trade resolution in time for resolution in amplitude i.e. if you were to look @ an over-sampled DAC output, it'll be a signal bouncing between logic 1 & logic 0 & will be pulse-width modulated (PWM) per the input signal. You'll look @ it & gasp for it has no correspondance to the input signal. Further digital signal processing of the over-sampled data converter output is needed before the music signal can be extracted. OTOH, Nyquist data converters trade resolution in amplitude for resolution in time i.e. if you look @ a Nyquist rate converter, it's output is highly correlated to its input signal.
More than you wanted to know, I think!! Hope that this helps

Thank you.

Are you a digital engineer? Is it accurate than that Nyquist converters are more time / phase accurate when compared with over-sampled DACs, all else being equal?

In any case, yours was one of the most lucid, informed answers I have read in this forum. Thanks. I learned something today.

Thanks for your kind words!
You ask a tough question! Nyquist rate converters & over-sampled converters are 2 quite diff. beasts with very little in common except for they perform the same function - D-->A. Diff. design tecniques are used, diff. pitfalls are looked into during the design.
Both designs can be made equally phase accurate & both designs can be equally botched!
In over-sampled converters some of the things one needs to consider are stability, quantization error, effect of in-band tones, non-linearity, which is are a diff set of criteria from Nyquist rate converters.
Which one is used depends on the application on hand & the cost factor.
Hope that this helps.