Vishal Kalita's collection of music cassettes has turned his residence in India's Assam state into a private museum. For more than a decade, the 30-year-old has been travelling across the country buying obsolete tapes, which he has carefully stored at his home in Guwahati city. The collection, which was opened to the public last month, also includes hundreds of CDs and rare posters of musicians from around the world. But it's the discography of Zubeen Garg, a singer and composer from the state,