Ok, with that extra information I can see where you are coming from! To summarise, I think you are saying that a CD can sound nearly as good as an SACD when played in two-channels through a state-of-the art DAC box.
In my experience most classical CDs have excellent sound quality, probably because digital mixing is kept to a minimum. I stopped buying vinyl as soon as CDs came out, but I am dipping my toes into the vinyl waters to try to see what all the fuss is about.
There is virtually no difference in price for me between new classical CDs and new classical SACDs but new vinyl is three times as expensive - I mainly buy through Presto. My local bookstore keeps second-hand classical records at about four bucks each, and possibly because I use micro-line stylii, most sound as good as new. The bookstore's main storage is a huge book barn, which has been expanded into a winery and wedding venue so I think records are just nostalgia for them.
Your Oppo seems to work fine as a transport outputting HDMI, which is the same as my Reavon experience. Personally I cannot see any point converting multi-channel HDMI to I2S (2-channel only) or feeding DSD into any DAC with a ladder architecture. DSD was invented to remove the need to balance the individual rungs of the ladder!

