Coming full circle from the Marshall multi-stack excess of the ’70s, today’s sound-system technology would allow a guitarist to use the tiniest of amps as a backline rig in a stadium setting.

In the early days of rock, high power and huge volumes pushed equipment to the limit.

Mr. Shoe came flying into our rehearsal space, shouting and waving his arms as if he were flagging down a taxi. “Your amplifiers are distorting," he shouted above our Yardbirds-style rave up. Obviously upset, he continued, “Your amps—they're making square waves."

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