I sort of mis-spoke when I said 'due to'. I should have said 'could very well be due to' instead. It is rumored that there are easily measured equalization and other differences between the SACD and CD versions of some otherwise identical recordings. Why would that be? Dunno. Could it make them sound 'day and night different'? I bet so. Could that be the reason it's done? The conspiracy theorist in me suspects it could be. Could this guy be lying? Sure. Would it be easy to discover? Yup. Has anyone done the measurements and said he's wrong? Not to my knowledge. Why? 'cause he's probably not lying. Am I motivated enough ot do it myself? No way. I really don't care.

I knew when I said it I was opening a can of worms. I can address those concerns, but in reality nothing I say will probably ever convince anyone to change their mind and no one has ever been able to back the high speed sampling or deep bit theories with any solid engineering or logical arguments that I found compelling.

So it's probably best to agree to disagree on this one peacefully. If you or others want to discuss it calmly and logically I'm OK with it, but I'm not interested in screaming matches, anecdotal evidence or emotional appeals. It may be best to let it rest as a sort of religious issue.

To address your points:

(1) No argument. Also has nothing to do with digital sampling method. An extreme case of this would be a brick at zero input, which exhibits zero distortion.
(2) Qualitative assessments are useful, but I suspect this could be traced back to quantifiable causes.
(3) DC-70K. I doubt anyone anywhere has a system that can put out meaningful levels of output over this range, although I'd sure respect anyone who does. Also, I can only hear (at reasonable levels) up to about 18 KHz. Few adult humans can hear much better than that.
(4) It's good not to scratch the surface I guess? Or is it bad? Anyway, nothing I can disagree with there. I will say that there's no waveform that cannot be accurately represented as a stream of PCM data.
(5) Not my problem. Also, DVD-A can often play in DVD-Video players, which are actually a growing market segment. Amazon has lots of shelves. Don't really see an issue.

And another thing, I know you know better, but PCM doesn't require a brick wall at 20KHz either. The CD audio format, a specific case of PCM, does. And my wetware does a dandy job of figuring out what parts of the signal are 'common' and forming an image on center. Is it distorted? Sure, has to be by definition. Does it usually sound OK? Yep. Are people that swear by this method idiots? Not necessarily. Is the original center mix of a real acoustic event distorted anyway? Probably. Do I use a phantom center? Nope. Have I? Yep.

Anyway, peace and have a good one.