The Rolling Stones still play extremely loudly.

The 'Brown Sugar' group were joined by Gary Clark Jr. at their '50 and Counting' show in New Jersey last December and he was surprised by how much he had to boost his own levels just to make himself heard.

He said: ''The thing that really tricked me out was how loud those guys play. My amp's usually on four to five, I had to open it up to eight to barely even hear myself.

''At the rehearsal, everybody was so welcoming. I thought, 'I'm just going to jam the blues with some folks, then it clicked that I'm talking to The Rolling Stones.''

Gary added the group's guitarist Keith Richards was particularly nice to him, because they like the same music.

He told Classic Rock magazine: ''Keith was particularly kind to me. He pulled me to one side and we talked about Howlin' Wolf, Muddy Waters. He said, 'I guess we both come from the same school of music, eh mate?' ''