Al,
please note the context and also requirements for relaxed anti-alias filtering; which comes back quite a bit to what we are talking about - just look to what Yuri recently said.
Yes, but relaxed anti-alias filtering is an issue of practical technical implementation, not of theoretical limits.
That is the constant confusion in these discussions, practical technical implementation vs. theoretical limits. As I noted in a previous post, I do not deny that hi-res may sound better in practice, but this is a different issue than considerations of theoretical limits to resolution. The technical limits of the CD sampling rate are right on the theoretical edge of what should still allow for transparency to the signal, and in hindsight should not have been, whereas hi-res has a lot of room top spare so that its practical implementation is easier (also with regard to dynamic range). Yet it is audiophile consensus that on top-level playback equipment CD still sounds better than hi-res on second-tier equipment, which in turn performs less well on CD than it does on hi-res. It's all about the quality of implementation.
Yet the debate here is not about the practical implementation of the CD format, and the considerable difficulties that this brings with it, but about its theoretical limits of resolution, especially when it comes to sampling rate (see thread title).