Nowadays, the concept of a "side project" — a long-term member of a band leading another combo part-time — is fairly common. Back in the '60s, it was practically unheard of. Guitarist Jorma Kaukonen and bassist Jack Casady were members of Jefferson Airplane, then one of America's most popular bands. Lifelong pals Kaukonen and Casady were baptized in the earthy intricacies of '20s and '30s blues, ragtime, and folk music. While those (and other) elements were integrated into the Airplane's psychedelic fabric, they yearned to play them straight up — and they did, regularly, during their mothership band's downtime. Kaukonen and Casady named their unit Hot Shit, but their record label got, uh, flustered, so Hot Tuna was born in 1969. They broke up in 1979 after Kaukonen and Casady deplaned Jefferson Airplane but reunited in 1986. Originally acoustic, they gradually became electric, mixing blues with rock 'n' roll. While Jorma Kaukonen's most recent album, the superb Stars in My Crown, finds him embracing acoustic sounds almost completely, it's anybody's guess whether Hot Tuna will be unplugged, amped-up, or a mixture of both this go-'round. But these proto-Americana forefathers will be worth catching either way.