The building’s walls sometimes shake with a sonic rumble. Other times, it’s like a spaceship is flying overhead or as if the electronic duo Daft Punk has reunited in this pleasant industrial park in Stafford, thirty minutes from downtown Houston. But it’s just business as usual at the workshop headquarters of Synthesizers.com.The company has made analog modular synthesizers for nearly thirty years. The instruments are based on the classic Moog (rhymes with “vogue”) synths of the sixties and seventies, but these modern-day machines are cheaper and easier to play. They are elegant, with black panels, silver knobs, and red lights. In the right hands—customers include Chromeo, Duran Duran, LCD Soundsystem, and numerous film and TV sound designers—they can create audio that is human and otherworldly,…