That was part of my question
There are a lot more questions all related to the encoding/decoding scheme of compact discs.
I jumped ahead and mis-read few things in order to answer the other questions. What I meant to say was that HDCD, SACD and XRCD are all technologies aimed at offering an effective resolution of over 16-bit, with an advantage of boosting the theoretical SNR.
The second question follows on from the first about stating there advantage and disadvantages of HDCD, SACD and XRCD.
So far I have only completed reading about HDCD and partly through reading websites on SACD. So far SACD seems better, so I guess SACD would offer the best sonic performance.
Haven't read a lot about PWM am ignoring it for now and will come back to it later.