by Stephen Thomas ErlewineTrouble's sixth album, Plastic Green Head, continues the progression of their multi-layered, complex breakthrough record, Manic Frustration. As the band blends in elements of progressive rock and psychedelia to their heavy, monolithic riffs, they don't dilute it -- instead the experimentations make it more popular. Plastic Green Head suffers a little from inconsistent material -- Trouble shouldn't be covering the Monkees' "Porpoise Song" and the Beatles' "Tomorrow Never Knows," no matter how wonderful the songs are -- but that doesn't prevent the record from ranking as one of their best. [The 2007 edition includes a bonus DVD.]