Square Garden. Joining the Stones onstage for an encore of "Sympathy for the Devil," Santana's guitar tone turned the band into fans of the brand, and the Stones' next tour exclusively featured Boogie amps. As the demand for his amps grew, Smith decided to move his workshop out of the Prune Music storefront to get away from the distractions of the store having become a busy local hangout. He relocated to what was formerly a plywood dog kennel, then, eventually, to his home. Smith produced a number of custom variations of the Boogie through the late 1970s, with options including reverb, a five-band graphic EQ, various speakers (most often Altec or Electro-Voice), koa wood jointed cabinets, and wicker grills. Upon the 1978 release of the Boogie's successor - the "Mark II" - the Boogie was renamed the Mark I. Smith ultimately produced over 3000 amps out of his home workshop in the 1970s. The 1980s and the Mark IIc+ As Mesa continued to grow, Smith moved the company to Petaluma in 1980 and continued to improve his amp designs to meet players' requests. Revisions to the Mark II resulted in amplifier milestones such as channel switching (Mark IIA) and the first effects loop (Mark IIB). Notably, the Mark IIC was voiced to "sound heavier and more menacing," and the IIC+ variant became popular with early heavy metal guitarists like Metallica's Kirk Hammett and James Hetfield, who was dissatisfied with Marshall amps at the time and wanted something "percussive tight and in your face." Smith has cited Master of Puppets as an example of the IIC+'s tone being able to compete with larger amplifier "stacks" typically used in heavier music, despite noting the amp "didn't fit the style." Throughout the decade, Mesa continued to produce combo and head amplifiers, and began production of rack power and pre-amps, developing power amplifiers such as the M180/190 and Strategy series, as well as pre-amps such as the Quad and Studio. Other models developed in the 1980s included the Mark III, Mark IV, the Son of Boogie, and the Studio .22. The 1990s and the Rectifiers As the 1980s came to a close, the complicated features and boutique styling of the Mark series began losing popularity in favor of simpler designs by Marshall, Bogner, and Soldano. Particularly inspired by Soldano's SLO 100 - itself derived from the Mark series circuits - Mesa introduced the Dual