Disclaimer: playing this mix for infants has not been shown to increase scholastic achievement scores in longitudinal studies. Similarly, blasting this through your speakers while studying will not proportionately boost your memory's retention rate. With the possible exceptions of Virgil Fox's Bach cover, Glen Campbell's rendition of "the last known hit written by an Italian composer," and Hugh McDowell's bitching cello solo, if Beethoven heard these tunes he would not only roll over and tell Tchaikovsky the news, but would also spit vitriolic venom in his lengthiest blog post since "I'm Not Actually Deaf, Suckers."
I would consider both Judgement Day and Rainbow "metal bands" and Rick Wakeman even snuck some Led Zeppelin into the epic romp "Catherine Howard." Di Meola, McLaughlin and De Lucia do a borderline job of proving they're classical guitarists and not just jazz fusion studs, but they did win the Grammy Award that year for "Best Performance by a Trans-Genre Trio Whose Last Names Are Clearly Indicative of What Language Their Ancestors Spoke." And if Beethoven doesn't like prog rock, "Mars" is probably what he hears in his own personal hell when either of the other two Emerson and/or Lake performances here is played.