I am not in favour of taking apart operas. I think they should be listened to, enjoyed as a complete work. Music makes sense in context, especially in a clearly defined context such as an opera. So what is this collection of orchestral opera fragments doing in my collection?
This was probably nothing more than a statement of my intent to find the complete operas in the future. I already enjoyed Maid of Orleans, and I saw Mazeppa live in the Nederlandse Opera (DNO). So what was to stop me from buying more?
Well, I never found them. Even in streaming it is not easy to find good recordings of these Russian favourites. Partly because not many have been made, partly because modern recordings are made less and less: it is really expensive, and there is no money to be made from them.
This record has an extra feature: it is quadraphonic. If you put this through a special decoder, you can add two extra speakers and enjoy a more spacious sound. This was an early version of surround sound. It is compatible with normal stereo sound, so I don’t hear it.
Specifically about the Sansui QS system used here, see https://en.wikipedia.org/wiki/QS_Regular_Matrix. From what I can see, this encoding was offered freely to among others Decca and Turnabout. This is an American Turnabout pressing.