@sns
@charles1dad
There is no question, I think, but that the best of the new DACs take Redbook further than before. My own experience is that the Musetec brings Redbook closer to high resolution than did the LKS, already close. All this has generated articles on whether there's any further need for high resolution audio in our DACs. Seems to me that higher resolution is not dead just yet for a couple of reasons.
I, for one, hear something special in "pure" DSD recordings, that is recordings that have not passed through any PCM processing. For me that is primarily DSD recordings taken directly from analog tapes. Yes, they're mostly rips of old RCAs and Mobile Fidelitys, but IMO they can be quite spectacular. As for new recordings, besides those that have been doing it for a while, PS Audio is now doing pure DSD recording. They probably have resources enough to make an impression on the market. And of course, SACDs are still being made, particularly in the classical field.
I have carefully compared some of the Nelsons Shostakovich recordings in their Redbook and 96/24 versions and can report a slight benefit from the latter, even to these old ears. It's small, essentially spatial issues, but it's there in my experience. It's a difference we crave. In some other comparisons I have not heard a difference. Would I have been satisfied with the Musetec-Redbook alone? Certainly. It has also been said that for high resolution recordings the mastering is better, that is, done more carefully, so yielding a better sound product. Does that trickle down to the Redbook file of the same recording? I don't really know.
Also, there are those who report beneficial effects using computer programs that do upsampling to the limit of their DAC, and even conversion to DSD and upsampling those also to the limit of their DAC. I'm in no position to question them. I have not done that to any extent myself. I control my music through a PC that is little more than a Chromebook. I could do it manually, but it's not worth the effort, for me.
So hirez seems still to be alive, if somewhat on its heels.