oh, geez...quite a few through the years. I'll list a few standouts; Billy Joel, Stevie Ray Vaughn, Jethro Tull (multiple times), the Grateful Dead, String Cheese Incident, Harry Conick Jr., Willie Nelson, Ray Charles, Led Zeppelin, Jefferson Airplane, Bonnie Raitt, John Prine (multiple times), John Hiatt, John Mellencamp, The Band, Dylan (multiple times), Poco, Bob Seger, Herbie Hancock, Chick Corea, Eddie Harris, Maynard Ferguson, Sheryl Crow, Santana, the Association, Blood, Sweat and Tears, the Turtles, the Young Rascals, Melody Gardot, Los Amigos Invisibles, Al Green, Rod Stewart, B.B. King, Aloe Blac, Lady Gaga, Arcade Fire, Yes (multiple times), Beats Antique, the New Pornographers, Black Keys, Mitch Ryder, Mountain, the Screaming Gypsy Bandits, Brandi Carlile, Mark Knopfler, MOE, Leonard Cohen, Rodrigo Y Gabriela, Paul Simon, Green Day, and a lot of blues and jazz guys. Never saw the Stones or Springsteen or JJ Cale...those are my regrets.