Well, it's a 5.1 mix, but it's not one that respects the quad mix, and in fact seems to be entirely missing the elements from the rear channels of the quad mix in some cases. I mostly wonder if we should be properly considering them making the quad mix available digitally at all.
Well, that is some of the problems with original Sony SACD releases. Some titles were the original mix, with added center, that can be switched off, and other titles where the mix was ruined. The O'jays is supposed to be original Quad mix, along with Isley Brothers (with swapped channels on 3+3). We were able to figure this out on these titles, but there are other titles we may not be familiar with. I didn't listen to as much Classical music back in the day, as I do now.
So if a mix actually has been destroyed, remixed, no way to get it back, then of course it would be good try to get D~V to get us the original mix. What we need to do, perhaps in another thread, is list which early Sony titles have the Quad mix intact, and those that have been ruined by remix. Can't imagine the list being too long or hard to figure out.
But speaking of the "Concerto for Orchestra," we also have this version, which has an original Quad mix from the 1970s, but was not able to get a Quad release at the time. If I understand correctly.
https://www.amazon.com/Bela-Bartok-...ion/dp/B06ZZ8PNVS?ref_=mw_olp_product_details