Livin' on the Fault Line fell between two of the Doobie Brothers' biggest-selling records. The album had no hit singles, and one-time leader Tom Johnston kept a markedly low profile (this would be his last record with the group, not including a later reunion). Despite this, Livin' on the Fault Line contains some of the most challenging and well-developed music of the band's career, with Patrick Simmons and Michael McDonald really stepping to the fore…