Does Native PCM exist or has existed ?

[opus101]

Pure 'native' PCM ADCs do exist, at least as chips. But I'm not aware of current production ADC boxes which use such chips. Therefore almost all PCM has indeed been through an S-D modulator (not very likely to be 1bit though) at some stage in its life.

 

I'd not pay as much attention to whether a DAC is S-D or R2R as to the particular implementation details.

[opus101]

32 minutes ago, PeterSt said:

Designing a DAC is quite exciting. For example, the PCM1704 has always been specified as being able to do 24/96. Still the datasheet gave hints to otherwise, and I just gave it a try at 24/768 and it worked. Since then the 1704 can officially do 768 (many people still don't know, but alas, the chip is EOL anyway).

 

The 'headline' sample rate for the chip is 96kHz but it was always assumed it would be used together with an 8X OS digital filter. The spec table shows only one rate for all those detailed measurements, which is 768kHz (96k*8).