But SACD is not PCM (Pulse Code Modulation) domain, it uses DSD (Direct-Stream Digital) using a totally different algorithm all together.
=> 2.8224 MHz or 64 times the CD audio sampling rate of 44.1 kHz and only 1/16th its 16-bit resolution.
So DSD on SACD is way out there in the Frequency Range (sampling rate), but way below the 16-bit (bit depth); and it sounds excellent (to my old set of ears).
Yeah I know, some of them SACDs were derived from PCM.
You said; 24/44.1 are "some" of the best digital you've heard. Ok, good, and what about 24/88.2? ...Or 24/96? ...Or 24/192? ...Or 32/352?
Me I thought that 20/88.2 or 20/176.4 is all you truly need. ...And if someone wants to add another additional 4 bits to make it 24 I don't have any objection. ...Heck, if 32 is your bag I still don't mind (it does have some advantage in some particular applications, if properly done).
* Some RB CDs were created from 20 or 24-bit (remastered). ...Still 16/44.1 though, just like the Crystal Disc. ...Unless true DSD was used.
...And that your playback device can read it properly and reproduce it too as is (Direct-Stream Digitally). ...From some $100 machine (Sony BD player) up to $80,000 one (dCS).