Comparing two performances Of Chopin’s Nocturne in Db, Op. 27, No. 2

I had a reunion with a childhood friend over Skype this past weekend, and our conversation drifted to concerts we both attended in the 1970's at Carnegie Hall. For me, one was memorable, the other, not. Horowitz had made a historic return to the concert stage that trumped Maurizio Pollini's scheduled performance in the same…