Armstrong and Ellington are two of the most important figures in 20th century American music, never mind jazz, so this 1961 encounter carries a lot of listener expectation. The band is Armstrong’s — Barney Bigard on clarinet, Trummy Young on trombone, Mort Herbert on bass, Danny Barcelona on drums — with Ellington playing piano and supplying all the tunes. Hearing Armstrong dig into immortal melodies like “Black And Tan Fantasy,” “Mood Indigo,” “Solitude,” “Cotton Tail” and more is thrilling, and his performances pack a surprisingly emotional punch. This is much more than mere showbiz; it’s a gesture of mutual love and admiration.