Boulez's Ravel box set is cause for rejoicing. This reissue is a comprehensive set of his complete Ravel recordings for CBS, in which we hear Boulez at his most expressive on record. His affinity and affection for Ravel are lovingly displayed all through this collection and his merits in this repertoire are well known (nearly matching them decades later in his DG remakes).
Yet, in the 1990, 3-disc, 20-bit remastered set, I was (and re-listening today, still am) bothered by odd spotlighting and some unnatural thickness in the mid-range, most notably in the horns and violas. Then in 2010, SONY extracted 5 selections, just enough to fill one CD, and remastered them in DSD. That set improved the originals only slightly. Spotlighting was ever-so-slightly reduced, but much of that annoying thickness was still there. And a touch of digital sheen was now apparent, glazing just perceptibly over the string tone. Frankly, the overall differences are so subtle, unless one has a very good quality sound system, they would be very difficult to detect. So I wouldn't classify that DSD disc as an improvement.
Now comes a fresh 24-bit remastering. And I can tell you this set sounds better than ever. Gone are almost all traces of spotlighting and thickness on the horns and violas. And the sheen on the violins has been cleaned up. What you hear now are more natural dynamics and a spaciousness which have not been previously revealed before on these recordings. No, it's not a jaw-dropping, dramatic change. But on a very good stereo system, the improvements are sonically and musically significant and thoroughly worthwhile.
Regarding the content, this box extends to 5 CDs (compared to the previous 3-CD set). In additional to the orchestral music, we now get Boulez's recordings of Ravel's music for solo voice (Boulez is at his most sumptuous with Heather Harper in Sheherazade, but I'm not fond of Jill Gomez in the 3 Poemes. Her tendency to begin notes with no vibrato just makes the voice sound unsupported and unpleasant). And in the spirit of absolute completeness, SONY has usefully added the Piano Concerto in G (although conducted by Ormandy, Entremont is the soloist, as he is on Boulez's Concerto for the Left Hand on disc 3) and also the 2nd Daphnis Suite, recorded in Cleveland 5 years before the complete ballet in New York.
So even if you already have some or all of this music on CD, I recommend replacing those previous issues with this one for its completeness and improved sonics. It really does sound wonderful. As a matter of fact, I compared this Ma Mere L'Oye directly with Slatkin's recent Naxos recording, and this new remastering makes it sound every bit as good.