Complex sentence: The first wave of 1980s experimental rock groups had few direct precedents for their sound; later in the decade, avant-rock pursued a relaxed, psychedelic aesthetic that differed from the self-consciousness and vigilance of earlier post-punk.
Split into simpler sentences: The first wave of 1980s experimental rock groups had few direct precedents for their sound. Later in the decade, avant-rock pursued a relaxed, psychedelic aesthetic that differed from the self-consciousness and vigilance of earlier post-punk.