Emerson, Lake & Palmer's most successful and well-realized album (after their first), and their most ambitious as a group, as well as their loudest, Brain Salad Surgery was also the most steeped in electronic sounds of any of their records. The main focus, thanks to the three-part "Karn Evil 9," is sci-fi rock, approached with a volume and vengeance that stretched the art rock audience's tolerance to its outer limit, but also managed to appeal to the metal audience in ways that little of Trilogy did…