You should take a listen to the stereo mix down tapes of quadraphonic recordings done by Marc Aubort at Elite recordings if you have a chance. Really awesome. He did one for the Ravel complete works for Orchestra VOXBOX set, and his recording of Ma Vlast is also excellent.i've owned 4 reels of 15ips 1/4" of JITPS for 13+ years now. great sound. really fine. listened recently thru the ATR-102/MR-70 and they have a new level of excellence to my ears. have some other 60's and 70's tapes that are very fine too.
but the best of Ed's Ultra Analog tapes are right there in terms of sound quality. smaller scale relatively simple performances but tip top sound.
it does not need to be old. does need to be tape. probably large scale classical great sounding tapes might be only in the past. love to see DG take the mix down tapes from the Quad 70's TOS performances and make tapes available from those. could be stellar with the production path they have.