THEY MAY NOT WANT TO ADMIT IT NOW, but there must have been a few really nervous people in the Roland offices when the JC-120 Jazz Chorus debuted in 1975. The post-modern design, drab green-ish hue, and ultra-clean sound certainly appeared to be out of step with the mid-’70s rock scene. The radio waves and concert venues were powered by amp stacks and gritty guitar tones, as acts such as the Who, Led Zeppelin, the Rolling Stones, Queen, the Sweet, Bad Company, Bachman-Turner Overdrive, Kiss, and others blasted out rowdy epics to kids in jeans and t-shirts. Of course, cleanertoned guitars that seemed readymade for the JC-120 were evident on chart toppers such as “Fame,” “Jive Talking,” and “Get Down Tonight,” and while disco was looming, no one cool really…