George Duke - SolusThe Inner Source arrived on the market as a double LP in 1971, after an initial plan to release two single LPs, namely SOLUS and The Inner Source. Both recordings were made in the same year, shortly after George Duke had left Frank Zappa's band and taken over the place of Joe Zawinul in the Cannonball Adderley Quintet. They are considered to be true highlights of Duke's work, an act of musical release with an audibly rapid development both on the keys