Founded in 2002 and operating from the corner of Goldfinch Street and West Washington in Mission Hills, M-Theory Music runs a dedicated vinyl and CD shop covering indie rock, soul, funk, jazz, reggae, hip hop, punk, electronic, and world music. The store buys used vinyl and CDs outright for cash or store credit with offers sized on condition and demand, and the shop's long in-store performance history feeds the same independent-music circuit as comedy and live rooms such as National Comedy Theatre. A rotating new-release wall tracks independent label drops alongside reissues and limited pressings, with a dedicated local-artist section for San Diego bands. Listening stations let collectors preview used copies before buying, and a 7-inch bin stocks singles going back to the early punk, soul, and reggae eras. The shop participates in Record Store Day each April with exclusive pressings, and the late-afternoon vinyl-browse traffic overlaps with the jukebox and DJ-night programming at The Lamplighter a few blocks east. Estate and whole-collection vinyl buyouts are evaluated at the trade-in desk, with pickup, grading, and cash-out pricing handled on lots ranging from single crates to libraries of several thousand records.