When Mr. Renzi performed he was rarely in the spotlight, but savvy listeners understood that his playing and arrangements helped the stars he was backing be at their best. The list of performers the pianist and arranger Mike Renzi worked with is amazingly long. And varied. Mel Tormé and Lena Horne are on it. Peggy Lee and Maureen McGovern are on it. Lady Gaga and Tony Bennett are on it. Big Bird is on it. Mr. Renzi, who for decades was one of the most sought-after accompanists in the music business, especially in jazz circles, died on Sept. 28 in Newport, R.I. He was 80. But, through the efforts of his estate, and his long-time friend and music partner, world renowned bassist, Paul Del Nero, Mr. Renzi continues to give to the music world with the release of a brand new recording, "Darn That Dream", on Club44 Records.