Here's a better challenge: You recall my stereo comparisons of Bix solos, with simultaneous playback of alternate takes. At the time, my only recourse for synchronization was to change the speed of one of the takes, to match the tempo of the other. The resulting differences in pitch made some of those comparisons barely listenable and others impossible. Now with Audacity, that hurdle is yesterday's mashed potatoes. Any of them can be synched perfectly. It's just the matter of figuring out HOW.
Some of the Bix alternates with widely varying tempi: