M. SCOTT MORRIS Let’s say you’re a pianist, but not just any pianist. You’re a solo improvisational jazz pianist. You might expect to miss a few meals with a job title like that. It’s Jan. 24, 1974, and you’ve driven from Switzerland to Germany. You’re tired. You feel a knot of tension at the base of your spine. You’re supposed to perform a concert at the Opera House in Köln, which hosted an opera earlier in the evening, so your show doesn’t start until 11:30 p.m. The promoter who brought you to town is 17, and she convinced the opera house swells to open their esteemed doors for a jazz pianist. You requested a Bösendorfer 290 Imperial concert grand piano for your show, because you require a quality instrument. She says no problem, and the opera house says no problem, but there’s a problem. The staff finds a Bösendorfer piano backstage, but it’s a baby grand.