One of a rapidly growing body of live Gentle Giant performances from the '70s that have begun surfacing on CD, Prologue is the next thing to a bootleg: the fact that the title is misspelled as "Prolouge" on the back cover and the spine is sort of a dead giveaway. The two-CD set encompasses two shows dating from the periods of In a Glass House and The Power and the Glory, respectively; the first disc and part of the second come from an April 5, 1974 concert in Munster, Germany, and the balance of the second disc is filled out with four numbers from an October 10, 1975 show at the Philadelphia Spectrum. The material is drawn from among the group's best work, from their prime creative years, though it is debatable if this is the best way of hearing it. That's especially true of the Munster material which, though it is a taut and bracing performance, is lacking in sound quality, it's sort of medium-fi, with the vocals somewhat weaker than the instruments. Much better is the material from the Spectrum, which comes close to the quality of an official live album, and shows off such pieces as "The Advent of Panurge," "So Sincere," and "Free Hand" to great advantage in a concert setting. Each of the members does get a showcase for his playing, and completists will have to own this set, but more casual fans will be disappointed by the amateurish packaging and uneven sound.