“I wonder what would happen if a giant tab of acid was dropped into the sea?” asked a member of the progressive rock band Nektar some forty years ago, recalled Roye Albrighton, Nektar’s guitarist and vocalist. Albrighton and his mates parlayed their curiosity into the group’s acclaimed second album, appropriately titled A Tab in the Ocean. Philadelphia’s ItsAboutMusic.com label has just reissued that recording in a deluxe two-CD set also containing a bonus “lost album,” In the Beginning: The Boston Tapes. This 8-track collection was recorded in 1970 and contains the very…