I have owned a good SACD player and while some of the SACD recordings I owned were impressive on SACD the redbook on my SACD player always failed to compare with the OPUS 21. That said the best SACD recordings are better than the best redbook even on an OPUS 21. There is just very little of really good SACD recordings. I don't think the typical SACD recording on a good SACD player is generally as involving as the typical redbook recording on an OPUS 21.
