Complex sentence: At a show at The Fillmore in San Francisco, during a performance of "Interstellar Overdrive", Barrett slowly detuned his guitar; the audience seemed to enjoy such antics, unaware of the rest of the band's consternation.
Split into simpler sentences: At a show at The Fillmore in San Francisco, during a performance of "Interstellar Overdrive", Barrett slowly detuned his guitar. The audience seemed to enjoy such antics, unaware of the rest of the band's consternation.