There is certainly no lack of good recordings of the Debussy piano "Preludes", going back to Gieseking, through Michelangeli and Arrau, and on to more contemporary pianists such as Thibaudet and Bavouzet. The twist in this 2-CD set from ECM is that Alexei Lubimov has deliberately chosen particular instruments for each book of "Preludes", a 1925 Bechstein grand for Book I and a 1913 Steinway for Book II. While I admit that my own ear is not subtle enough to discern all the differences in tone color between the instruments, whatever his own rationales were for his choices, the choices work. Lubimov has a splendid touch on both instruments, and his performances are wonderfully self-effacing and feel quite right, drawing all your attention to the music and not to himself.
The other factors that make this set truly stand out are the inclusion of 2-piano versions of two of Debussy's orchestral works, "Prelude to the Afternoon of a Faun" (in Debussy's own transcription) and the "Trois Nocturnes" (in Maurice Ravel's transcription). Once you mentally prepare by forgetting the orchestral versions, and accept that those particular tone colors will not be present by definition, both of these versions are also highly enjoyable in of themselves. In fact, at the risk of slight heresy, I actually found the Ravel transcription of the "Trois Nocturnes" more effective in making me forget the orchestra than Debussy's own arrangement of his own music. Perhaps that is because one loses not only the orchestra in the "Trois Nocturnes", but also the women's chorus in the last movement, 'Sirenes'. Lubimov makes use of his two pianos by dividing duties between himself and his colleague, Alexei Zuev, as follows:
"Trois Nocturnes": Lubimov - Steinway, Zuev - Bechstein
"Prelude to the Afternoon of a Faun": Lubimov - Bechstein, Zuev - Steinway
Zuev makes a fine partner with Lubimov in the two-piano works. I believe that Zuev is a student of Lubimov, so perhaps it's no surprise that they work well together.
The overall running time is just about 112 minutes, not quite full measure for 2 CDs, but Lubimov's accounts of the two Books of the "Preludes" appear to run between 80-81 minutes, which pushes the limit these days for a single CD. But the inclusion of the two two-piano works is very much worthwhile on their own terms, regardless of running time. If you are interested in Alexei Lubimov and are a fan of Debussy's piano music, this set is highly, highly recommended and very much worth your while.