I've used that exact method a couple times. I did do the reverse RIAA digitally with EQ. Works well and I am surprised at how well phono stages of good quality worked.
Right, as @Blumlein 88 indicates, the SACD contains a CD-compatible 44/16 stereo layer, plus a hirez DSD layer containing both the stereo mix and the Mch 3.0 mix. A Mch SACD player allows the choice which of those 3 programs to play. And, it is easy to switch between the more comparable DSD stereo and DSD Mch, though switching might force a restart from the beginning of a track. I do not play from optical disc, however. I now play my SACDs from files ripped to my PC and NAS.
I didn't know about these discs but I did know the original recordings were 3-track. It is on record that Wilma Cozart, who directed all the recordings, and George Piros, the cutting engineer, blended the 3 tracks into 2 on the fly whilst cutting the lacquers, presumably to avoid the loss of an extra analogue copy. They "strove to reproduce the full dynamic range of the original tapes without jeopardising reliable stylus tracking. It was not easy to overcome the limitations of the tape-to-disc process, defying the inner groove perils, cutting head quirks and unpredictability of lacquer quality".
Frank - the Mercury and RCA 3-channels appear to me to have been balanced for a properly calibrated, equal channel loudness playback setup, as all Mch recordings should be. No adjustments to center volume are necessary beyond that. However, it is possible that the final overall loudness is slightly greater than 2-channel due to the addition of the center channel on playback. The impression, as I recall, is mainly of a better center stage image and "fill", including apparent depth.I didn't know about these discs but I did know the original recordings were 3-track. It is on record that Wilma Cozart, who directed all the recordings, and George Piros, the cutting engineer, blended the 3 tracks into 2 on the fly whilst cutting the lacquers, presumably to avoid the loss of an extra analogue copy. They "strove to reproduce the full dynamic range of the original tapes without jeopardising reliable stylus tracking. It was not easy to overcome the limitations of the tape-to-disc process, defying the inner groove perils, cutting head quirks and unpredictability of lacquer quality".
The balance of the original recording was entirely achieved by moving the microphone position relative to the instruments. I was taught to do the same for my own recordings when I first started.
On the Mercury SACDs do you know how the relative levels of the 3 channels were balanced? I am sure a digital recording can get the full dynamic range and frequency response of all 3 channels, but given the microphone layout I would not imagine the raw balance of the 3 levels would be correct unadjusted?
I am afraid I only use surround for the few films I watch in my listening room and have no center channel any more since it would be physically in the way in the current layout, so the Mercury SACDs would be a waste for me
