How to tell if a CD is Encoded?

All SACDs are DSD

some CDs are based off analog tapes that have been remastered in DSD

some DSD recordings can be purchased as CDs

we seem to be confusing the recording and mastering (which is interesting) with the final media (which is the relevant point of your question)

as far as commercial silver discs go its red book pcm or 128 DSD that's it! Standards are standards

If it's this release it's the SACD, if not it's a CD only
https://www.discogs.com/Beethoven-Karajan-Berliner-Philharmoniker-The-Symphonies/release/3344481

All versions can be found here
https://www.discogs.com/Ludwig-van-Beethoven-Symphonien/master/30029

@cheeg you're still a little confused

RedBook = CD Standard = 16/44.1PCM

Any other PCM (e.g. 48/96) is not redbook and is not encoded on a CD, you can store these files on a CD ROM drive but it is not CD standard

SACD as a standard is always stored on a SACD format disc, not a DVD (that's another thing entirely). Most SACD are dual layer with one layer that plays SACD and the other that plays redbook

Higher rate DSD (e.g. dual DSD, or quad DSD) can be downloaded or played back from other storage media but there is no commercially available disc format for them

But it seems you have a plain old vanilla CD set

To which I’d add that you can also change how you listen to the final medium.  For example I listen to my red book upsampled to dual DSD, sounds better that way to me in my system

so to the OPs follow on question about ladder vs delta dig DACs, it depends 🤪

Not at all @cheeg. Consider an analog pressing of an LP that says "remastered on a vintage Neve console from the original master tapes" that doesn't mean you're getting a tape, it just describes the techniques the mastering engineer used to create the final mix.

It's exactly the same in digital. When SACD first came out and DSD A/D became available it was a selling point to say "mastered in DSD" (such as the Rolling Stones issues that were mentioned) and many CDs and LPs were sold on this basis.

As to the value in upsampling -- agreed you cannot create information that doesn't exist but there is much logic to a higher sample rate in terms of the avoidance of the need for certain deleterious filters, and not least a better fit with your D/A. In a full DCS stack, as I have, you can try any combination of input and output rates you like and select what sounds best to you.

@cheeg no, not any book -- but Google is your friend, like this for example, a nice discussion and examples
https://audiosciencereview.com/forum/index.php?threads/understanding-upsampling-interpolation.1447/