Shortly after 18-year-old Maurizio Pollini won the 1960 Chopin Competition, EMI gave him a contract and they recorded Chopin's Piano Concerto No. 1. Pollini then recorded the two sets of etudes, Op. 10 and Op. 25, that same year, but would not let EMI release the recording, partly because he did not want to be pigeonholed as an interpreter of just Chopin. Of course, he would later go on to record all of Chopin's music for Deutsche Grammophon with great acclaim, doing the etudes in 1972. In 2012, the Testament label remastered those original EMI tapes. 

"It's always interesting to compare the same works at different times in a performer's career, and in this case both are eminently recommendable and enjoyable for different reasons."
All Music