@ Feinstein’s at the Nikko, 222 Mason Street. The all-male string quartet returns to Feinstein’s as the classically trained foursome perform pop/classical mashups featuring tunes made famous by Stevie nicks, Rihanna, Queen, The Beatles, Lady Gaga, Henry Mancini and more. 8pm. Continues January 19 and 20. feinsteinssf.com