I like the acoustic stuff myself.
Just don't use Kentucky Colonel's Appalachian Swing. It has strange phase problems.
Was designed to be a center mic recording and the image surrounds you, walks a around you, and dizzies you at times.
Grisman's label has good stuff, Sam Bush stuff
Use a good vocal recording like Buena Vista Social Club. It will pass through the crossover frequency on vocals.
Listen to hear if the vocalists move aound.
Stereophile markets a few good two-mic recordings with your mind in mind. That might work for you.
Lots of great stuff on archive.org
two mics and a jdisk may be a bit too dramatic for speaker imaging depending on placement, but in the sweet spot... weeeel-dawgies !